It won't work with a local game, you need to play a game via internet so you have lag. Without lag this bug can't be reproduced.
It works particularly well for some units I think, the others are just wont work. With the help of the autokey tool and the cheat mod I found that those combination has the greatest possibilities to upgrade double equipment.
OKW ober - LMG34
Wehr grens - LMG42
Wehr Pios - Flamers, minesweepers
Weirdly it can't be done on soviet combat engineers, secret Axis buff confirmed Kappa?
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and, tested in skirmish of course.
Relic Entertainment
cblanco ★ 
보드카 중대 
VonManteuffel 
Heartless Jäger 
