Deduplication in projects splits editor applies across maintainers & dependencies even if one is set to 0%

[efstajas]

To reproduce:

1. Edit a project's splits
2. Set maintainer / dep split percent to 50%/50% (or any other configuration where neither is 0)
3. Continue and add some address to maintainer list
4. Go back, and change maintainer / dep split to 100% dependencies
5. Continue, try adding some address as before to dependency list

Problems:

• You can't add the split due to deduplication, even though maintainers are set to 0%
• When you click back, you go to maintainers list screen again, even though maintainers are set to 0%