If a view is present multiple times in the same module, the "last
instance" is going to win (by replacing any previous instance's arch
with its own).

Most cases of duplications are probably views which got moved then
either not removed (from the original location) or revived (through a
forward-port), the first instance can just be removed entirely.

For the few which seemed to be more than just trivial mistakes, merge
the two views instead.

closes odoo/odoo#44463

Related: odoo/enterprise#8107
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>