Exalted Orb potential bug?

I bought a crossbow from the vendor with five mods on it and high physical damage due to a 118% increased physical damage mod. Gave it to my husband and he exalted it to add a sixth mod on it. He got light radius (unfortunately), but the physical damage also drastically reduced (35% increased physical damage) essentially bricking the crossbow. We are currently level 62.

Not sure if there is a chance that that can happen?

Shouldn't from an exalt. Are you sure he didn't throw a Vaal (red) orb on it instead? That would have the possibility of doing what you described.

Definitely didn't corrupt it. Light radius got added and increased physical damage was reduced. It wasn't corrupted. It is as if light radius overwrote the second physical damage mod.

I have also had an issue where adding a 6th mod just consumes the exalted orb and there is a bug thread on that too. Think when it has a double mod there are bugs on rares with exalting.