Low ceiling clearance non load-bearing door opening question
This is perfectly fine. There is in fact a whole building science based protocol for not using double top plates or double studs even on structural walls. If the name comes back to me I'll provide a link to it.

Advanced Framing. Developed 40+ years ago and still not accepted by half the carpenters who learned from daddy who learned from daddy who...learned from the guy who's daddy thought he was nuts to move out of a perfectly nice cave.

The only possible benefit of a double stud in this application would be if you wanted to use 3-1/2" hinge screws. Sections of 2x4 scrap scabbed onto the stud in the right places would to that just as well.