Uh, I have a recommendation for a workaround. You can clone the submission - that'll probably work.
Drag the mp3 you used for the first one into the edit screen and start remaking the map as you normally would (set the sliders and copy the BPM/offset). From there, you can close the beatmap, open your original .osu file, copy all the hitObjects (they should be the last category of the .osu file) and paste them into your clone copy.
A shorter alternative would be to manually edit the header information of the .osu file. This is much faster but I don't know how tight the beatmap creator security is.