Routing at the Same Time

This was asked and answered in the Impetus WhatsApp group.

Assume both units in melee have a VBU of 1, and both are disordered. In the ensuing melee, both units roll one hit.

If one unit fails its cohesion test, that unit would take a permanent loss as usual, and consequently be eliminated. If the other unit passes its cohesion test, it too would rout and be eliminated due to the accumulation of disorder (being disordered while already disordered results in a permanent loss). Thus, both units would be eliminated as a result of the melee.

Yes, it can happen. Destroyed Units does't mean all dead, but simply that the Unit is no more relevant on the battlefield.