One flyback with two transformers
If this is about two flyback cores and windings, then the load on the (#1 core) secondary winding may mismatch the load on the (#2 core) secondary winding, leading to different voltage/time during the 'flyback' phase.  So, there's no
way to prevent DC currents in one core from changing its inductance, and
ruining the match (even with the primaries connected together, i.e. in 
parallel).

It's feasible, but may drift unpredictably from 'nominal' behavior.

Matching is improved by winding multiple secondaries on the SAME core,
which no longer requires multiple primary windings.