Telling apart newly out and proud NBA player Jason Collins from his identical twin brother Jarron Collins just got a whole lot easier.

Jason and Jarron were spotted leaving "Jimmy Kimmel Live" in Hollywood on Wednesday looking pretty similar as usual, except for one thing ... Jarron wore a shirt that highlighted a major difference between them.

As a joke, Kimmel gave Jarron the "I'm the Straight One"  t-shirt during his interview on the TV show last night ... not that there's anything wrong with that.

Jason Collins -- the first active pro athlete to come out as gay -- has already hooked up with a new posse, led by none other than Lance Bass! Teamwork is fabulous, ain't it?

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Jason Collins is not currently the member of any NBA team, but he's part of a different club of sorts these days ... and membership gets you a congratulatory handshake from Lance Bass. 

We spotted Collins and Bass outside Boa in West Hollywood Friday night. Collins was there with his twin brother Jarron and Bass was there with a group of buds. Our photog asked Jason about his dating life ... but the bballer prefers to keep his personal life close to the vest. 

It's interesting -- some people who come out want everyone to know everything about their romantic life -- but it's not the same for everyone.

Ex-WNBA star Carolyn Moos says her ex-fiance Jason Collins burned 8 fertile years off her womb's life -- and now she's planning to freeze her eggs before her biological clock stops ticking.

Moos previously said she had a life plan to have kids with Collins during their time together -- and after she learned he was gay, she felt the NBA player shattered her dreams.

34-year-old Moos says she still wants to have children -- but she's concerned she might not meet Mr. Right until she's too old to conceive ... so she's taken steps to have her eggs frozen later this month in case she wants to undergo in vitro fertilization sometime down the line.

"So many women think about this as a plan or option ... but few have had 8 years taken away from them like I did."

Moos says the procedure will cost around $10,000 -- but she's hoping to get some financial backing from any production company looking to capture the journey for a documentary.

So far, it's unclear if she's had any offers.

It's not all love for the first major (active) pro athlete to come out of the closet ... NBA player Jason Collins has also been the target of online death threats since announcing he's gay.

The homophobic threats began appearing on Twitter right after Jason's big coming-out interview with Sports Illustrated. Among the venom ...

-- "Yous a dead f****t talkn on tv Boy."
-- "Listening to Jason Collins describe his gayness as 'beautiful' makes me wanna puke. And kill him."
-- "Jason collins comes out the closet! Kill that biiitttchhhh!!!"
-- "First jason collins say he gay.. Now he on espn w lipgloss on  kill him now !!!"
-- "Jason Collins should get the death penalty lol how u a 7 foot gay dude lol the west is crazy smh"

In the S.I. article, Collins says he doesn't expect everyone to embrace him ... but it's unclear if he expected this kind of hatred.

We reached out to Collins for comment -- so far, no word back.

The woman who was once engaged to NBA star Jason Collins tells TMZ, she had NO CLUE he was gay at the time of their relationship ... in fact, she only found out last weekend ... and she was floored.

Carolyn Moos (who played a few seasons in the WNBA) dated Collins for seven years and was engaged to him until they broke up in 2009 ... after Collins pulled the plug on their wedding.

Carolyn tells TMZ, she never once suspected he was gay, so the news is shocking. She says Collins eventually revealed everything last weekend -- just days before his big announcement -- and said that his homosexuality was the real reason he ended things with her.

At the time of their breakup, Carolyn says Jason gave a bunch of BS reasons for calling it quits ... and she could never understand what went wrong, until now.

Carolyn -- who's back on the hunt for Mr. Right -- tells us, "It's very emotional for me as a woman to have invested 8 years in my dream to have a husband, soul mate, and best friend in him. So this is all hard to understand."

She adds, "I care about [Jason] tremendously and only want the best for him. I want Jason to be happy for a lifetime and stay true to who he really is, inside and out."

NBA star Jason Collins -- who instantly became a national symbol as the first openly gay professional athlete currently playing -- says he doesn't know any other gay players in the NBA.

Collins appeared on GMA this morning ... saying he always knew he was gay but fought it hard. 

Collins says he was engaged at one point but called it off, because he felt he would be getting married for the wrong reasons -- he felt he was doing it to convince himself that was the life he should lead.

Collins praised the Prez for calling him and voicing support, and also said one of his true heroes is tennis legend Martina Navratilova ... who has been openly gay for years.

​Not everyone in the NBA is thrilled about having a gay dude in the league -- in fact, there are definitely some "closed-minded" haters who are gonna have a hard time with Jason Collins ... so says NBA star Antawn Jamison.

The Los Angeles Lakers player was hangin' out in Beverly Hills today when we asked about Jason's big announcement ... and the 36-year-old veteran had a lot to say.

Antawn -- who's been in the league since 1998 -- told us he's glad Jason came out ... and he's happy the guy can "be who he really is."

But Antawn says not everyone feels the same way -- telling us, "Of course, you're going to have some closed-minded people, let's be realistic."

"That's life."

We also asked Antawn about the ass-kicking the Lakers got from the Spurs -- and the guy had a pretty good explanation. Check out the clip.

Mike Wallace needs to learn how to RESPECT gay people ... so says the Miami Dolphins organization, which says it strongly condemns the comments made by their star receiver.

A rep for the NFL team tells TMZ ... the Dolphins took immediate action once they learned about Wallace's homophobic tweet, in which he condescendingly questions why Collins would want to "mess with other guys" when there are so many beautiful girls in the world.

The Dolphins tell us ..."Mike Wallace has apologized for his comments, and we have addressed the matter with him."

"Mike’s comments do not reflect the views of the Miami Dolphins. We believe in a culture of inclusiveness and respect, and any statements to the contrary are in no way acceptable to our organization."

"We will address the entire team about our policy of inclusion and make sure they all understand the importance of respecting individual choices.”

Wallace has since deleted the tweet.

TMZ spoke with a rep for the NFL, who tells us the league office will review the situation -- and decide if the player will be fined or suspended.

Well, that was quick ... TMZ has learned Jason Collins has officially been asked to lead Boston's pride parade this summer, hours after the NBA star announced that he's gay.

A rep for parade tells TMZ, “Boston Pride is formally inviting Jason Collins to be a Marshal in the 2013 Boston Pride Parade ... Boston Pride is proud that our annual celebration helped to inspire Jason Collins to make his groundbreaking decision to come out."

You'll recall ... Collins told Sports Illustrated that the Boston Pride Parade was one of the main reasons he came out, claiming he always wanted to participate ... but couldn't because he was scared of public scrutiny.

Collins said he planned to march this year on June 8th -- but now he could be getting the VIP treatment instead ... which may or may not involve a bunch of half-naked men dancing in briefs.

... Miami Dolphins wide receiver Mike Wallace!!

Just HOURS after NBA player Jason Collins announced he's gay, 26-year-old Wallace took right to Twitter to provide the first ignorant comment.

“All these beautiful women in the world and guys wanna mess with other guys SMH (shakin' my head) …”

30 minutes later, Wallace deleted his tweet and replaced it with a half-assed explanation:

"Never said anything was right or wrong I just said I don't understand!! Deeply sorry for anyone that I offended."

Fun Fact -- Dolphins are one of the few animals that engage in gay sex!