Revert "Refs #2283: msc.target - do not create duplicate records"

This reverts commit 22fdecd7939f176eead92332cdf2bb6f86d8de06.

There is a problem with id_group field of target table:

It seems this field is used in web UI.

Way to view problem:

1. Make a dyngroup with all Windows
2. Launch a command on this group
3. Make a second dyngroup with same criteria
4. Launch a command on this second group

As you can see in Audit page, the group displayed for these 2 commands
is the second group.