Bug 34146: Do not allow multiple copies to crash server

Bug 34146: Do not allow multiple copies to crash server

Currently hardcoded to 1000.
Can be refined later. Let's first prevent this kind of accidents.

Test plan:
Add additem.pl. Edit the 1000 to 2. Restart all.
Add 3 multiple copies. Notice that you got 2.
Revert your code change.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>