The differing terminal capabilities don't jive with a diode module.
Toshiba case size 2-109A4A is found on 'GTR' modules that harbour 500V/1.2KV, 200A/400A IGBTs. Darlingtons have a fifth (signal) terminal on the same body shape.
Emitter in the middle (M6) Kelvin terminal at extreme end (M4)
Typical part numbers:
MG400H1US1 500V 400A MG300N1US1 1KV 300A MG300Q1USI 1.2KV 300A
They all have internal anti-parallel (CE) diodes built in.
If it's a fet, it'll have a lower saturation voltage, at lower current.
If it's an SCR or triac, it'll latch.
RL