(possible)=Concentric Attack bonus halved, if same formation OHQ involved

[zgrssd]

According to the manual:
"The Concentric Bonus will be halved if Units from multiple HQs are involved."

However I noticed that effect if the same units OHQ is involved. Using the OHQ as the 6th unit of a complete encirclement, will drop the concentric attack bonus to 100% (half of 200%). Similar effects happen with less severe encirclements.
Of course, this may be intentional to avoid sendign the OHQ into battle.