Are they both the same o/p power rating?
If so they will likely have the same power rated pump diode.
Is there a photodetector on the o/p for closed loop brightness control?
If there is the following would be dangerous so do not try. If not...
Assuming the same pinout of the head and the same Peltiers and thermistors used for TE control then the only difference will be the temperature settpoints of the pump diode TEC and the Crystal TEC.
If they are electrically the same then you should be able to mix and match and then go with the combination which gives greatest o/p power after a 5 minute warm-up.
Rgds,
Robin
Lasers and beer don't mix. After 2 beers I lose coherence.