Last night server lag happened while I tried to refill the Reversasigne from the item shop. The dialog gives me no response, so I clicked on the purchase button multiple times to see if it could work again. And what's happening is that I found 35 Reversasigne added to my inventory after the lag is ended!
Today I tried to purchase some Reversasigne to see if the game will fix the number, but it turned out the limit is broken, and I can buy as many Reversasigne as possible from the shop???!