The dude's leanin' more towards Duke, now ... 'cause Drizzy's added a FULL R.J. Barrett Montverde Academy basketball uniform to his insane collection ... and he's proudly showin' it off.

We all know the 6 God has a TON of rare prep jerseys -- from John Wall to Boogie Cousins to Barrett's Duke teammate Zion Williamson.

The newest addition might leave some people scratching their heads considering Drake's a big BBN fanboy ... and Barrett's tearing it up for the Blue Devils this season.

It's especially interesting because Barrett destroyed Kentucky in his college hoops debut earlier this season with 33 points and 6 assists ... but we take it Aubrey's had some time to heal.

The only explanation here -- Drake's pride for the North outweighs his Kentucky fandom ... and considering Barrett's one of the best Canadian hoopers since Steve Nash, he's probably cool with pissing off a few 'Cats diehards.

But, the full jersey AND shorts combo, Drake??

Sheesh.