1) Coding all 25 as separate 0,1 variables. This allows us to see more nuanced results, which is preferred!

2) Coding the two variables as two dummies (0, 1, 2, 3 etc), and (0, 1, 3, 4, etc.).

My question: I assumed I would get nearly the same result given this is essentially controlling for the same thing. But I'm seeing different results for the IV: a weakly positive coefficient for approach 1, and a weakly negative coefficient for approach 2. So my question is why is there a different result/sign reversal in the (pretty weak) predictor variable? This, to me, is weird.

I would really appreciate any input you may have on this - and what approach is correct - or if there may be something else wrong. Thanks so much! Kacie