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Sabrina Carpenter is seeking court-ordered protection from a man she says showed up to her home less than 24 hours after being arrested for allegedly trying to enter her front door ... TMZ has learned.

The singer's legal team beelined it to court Friday and filed a petition for a restraining order against a 31-year-old man named William Applegate ... according to new legal docs obtained by TMZ.

Sabrina claims Applegate showed up at her L.A. home on May 23, unannounced and uninvited ... and she says it was "clear to [her] that his approach was deliberate, calculated and aggressive, which is deeply alarming."

The filing includes photos from Sabrina’s Ring camera ... showing a man at her front door.

In her declaration, Sabrina says the man tried to open her front door and then rang the doorbell. Sabrina claims her security confronted him, but he refused to comply.

Sabrina says Applegate pretended to know her -- she says she doesn't know him -- and did not leave until cops arrived and arrested him.

And, get this ... Sabrina claims less than 24 hours after his arrest, Applegate returned to her home on May 24 and left when security told him to bounce. She claims he showed up again on May 25, prompting another police response.

In her declaration, Sabrina writes, “William Applegate is a complete stranger to me. I have never met him or communicated with him in any way. I have no desire to meet him or communicate with him.”

Sabrina asked for and was granted a temporary restraining order requiring Applegate to stay away from her, her sister Sarah and her sister’s boyfriend, George.

There's a hearing set for later for this month to determine whether to extend the TRO to a permanent order.