try doing a +- swap on one driver....probably the tweeter.
IF the crossover phases ADD at the crossover point, it may be too much. If the original crossove was such that the speaker had to be wired in or out of phase to be correct, you may simply need to swap......
Example: my maggies have a 1st order hi pass / 2nd order lo pass. The 2 drivers are wired out of phase. Good even response thru the crossover region.
IF I swapped the tweeter, it simply wouldn't be or sound right.