The concentration of solvents for different durgs are different. So, if mixed together, some compound might crystalize due to lowered solvent concentration. That's my opinion here
There is no problem mixing all in one vial I have done this before for "leftover cycles". They are not going to crystallize, the only one of those three with low solubility in oil is the prop, and mixing it in with the others would help with solubility/pain.