dovecot´s multiple quota roots

I am trying to find out how Dovecot behaves when there are multiple quota roots. I could not find something authoritative on this. For example, on a nicely running server that used fs quota I now have in 90-quota.conf

plugin { quota = fs:Mail Quota:user:mount=/Mail quota2 = maildir:Mail User Quota }

When I do

...

doveadm quota get -u atrige01 Quota name Type Value Limit
% Mail Quota STORAGE 80036 204800
39 Mail User Quota STORAGE 79306 -
0 Mail User Quota MESSAGE 304 -
0

Apparently both STORAGE quotas values are the same. The question is which of the two is being used by Dovecot. If I insert a limit on the maildir quota which of the two will be used? I am using Dovecot 2.2.12.

thank you