If you want to be attuned to weapon then no.
Reason for that is simple - Kyber crystals were sort of Force sensitive. Each Jedi would select (and be selected by) one matching his own personality. Therefore, crystals would become green, blue, and in some rarer instances violet, white or yellow. Sith and other darksiders would bleed crystal and it will become red . So, even those who constructed weapons made of two crystals (Maul, Temple Guards etc...) would have both blades in same color.
Both Jedi and Sith would build their own lightsabers using the Force, therefore it could be implied that they would have to be attuned to Kyber crystals in question to achieve this. Of course, I assume it would be possible to somehow join two already existing sabers into one saberstaff, but I doubt this weapon would be of sufficient quality.