[IMP] avoid potential error when specifying duplicated fields in read
[IMP] avoid potential error when specifying duplicated fields in read

Can't reproduce on my browser/machine, may be config-specific, but doesn't really hurt either way
vnc-biz/openerp-web,vnc-biz/openerp-web,vnc-biz/openerp-web,vnc-biz/openerp-web