Quota over exceeded

Uploading file works fine with quota, when limit is reached you quet an out of quota response.
But, if you copy or transfert files between your libraries, or from a shared library, you can overcome the quota.
Is this normal ?
I’m using linux seafile CE 6.0.6, and this behaviour is present since the begining ( v4.2 I think), and I noticed the same on the demo site (1,5G/1,0G used)