I´m doing a Western Blot for total H3 and I´m getting one band slightly higher than expected.

I am using the acid extraction method, and the first time I did it (with the help of a PhD from my lab) I got good results and only one band.

I did the extraction by myself but now I'm getting two bands. I have tried boiling the sample (prior to load) for longer, I've added B-mercapto and DTT and I still get two bands.

I have also tried running both samples (the ones that I extracted with my coworker and the ones that I did by myself) and the difference is clear. The two bands add up to the proportion of the one band from the first extraction.

Have you experienced something like this before

Thanks