I was not trying to talk you into using just one frame, I was trying to stress that it can go either way, but not seeing more details, I can not suggest which way to go.
Using two frames is perfectly fine if you, (the author of the code), has determined it is the way to go.
In the end the difference is using two frames and hiding one is keeping two frames in memory instead of one.
Don't let me talk you out of your decision, but if I was going to pick, I would rather have just one frame that didn't change size, shape, and possibly position during use, and provided all of the functionality I was going to use, but that is just my opinion based on not knowing any of the details