Archie Harrison Mountbatten-Windsor

Prince Harry's paternity leave is already over, and he's back on the job ... as a model. While Master Archie's back at the palace filling diapers, his pops is all smiles in the Netherlands ... happily showing off some baby gifts he'll be bringing home. Harry's back on the road -- just 4 days after…

9:05 AM PT -- If you're the betting type, and the type who loves a long shot ... you might have just cashed in big time. Ladbrokes, an online betting site, had Archie odds set at 100/1. Congrats if you just came up. And the Palace wants to make it clear ... his name is Archie, NOT Archibald. BTW…