Order edit issue (when change product quantity) PS 1.4.0.17

[Artizzz]

Hello all!

I tested order editing, I made test order and then I try to cancel some quantity, and then when I was canceled that quantity i get this - "Warning: Ls 28,070.11 paid instead of Ls 28,069.95 !".
In order used payment method - cash on delivery. (how can someone can be paid me when he has chosen COD payment method, it doesn't make any sense)
What does that warning means?
This is bug or what?
(PS version 1.4.0.17)

EDIT:
with other payments methods the same problem.

Best regards,
Artizz

[Artizzz]

in attachment I add what I discover.