I use Nestopia on a keyboard, so it's bound to happen that I hold left and right simultaneously at some point. Though, I have Nestopia cancel any L+R inputs, the problem emerges when I'm preforming Devil's Spell. Instead of releasing right to clip into the pipe, I hold left to cancel right (L+R). Which is basically exploiting the emulator. It seems kind of "cheaty" to me, so I'm just asking to clarify if those are valid inputs, since "right, release" and "right, right+left" output the same thing. I'm still kind of new to SMB2-J, so I'm sorry if this is just me being paranoid.

Turbo/Autofire and left+right/up+down are banned. <- I copied that straight for the rulelist. So it's easy to say L+R isn't allowed. Also, if you're a beginner to Lost Levels speedrunning I recommend to not go for any glitches in the game. It's better to just get a simple PB first.

That wasn't my question though (though I understand, I'm horrible at explaining). I meant I have L+R disabled on Nestopia (meaning pressing L+R outputs nothing). So I could technically opt for doing "R, R+L" instead of "R, Nothing" since they would do the same thing. I was asking if that was allowed

The L+R input is never registered so its not against the rules.

Kinda up to you if you feel good about submitting runs that exploit the emulator though.

I just realized I'm actually doing a quick left and then right. So I'm not actually holding L+R. I guess problem solved?

As long as the game isn't actually registering L+R being pressed at the same time, you're fine. The cancelling out thing essentially has the game see you're not pressing any direction.