backend: duplicate key conflict when adding the same contract across multiple orgs

[SyedAhkam]

How to reproduce

1. Create an org
2. Create another org
3. In the first org, add a contract
4. In the second org, add the same contract with the same address

Expected behaviour

It should be allowed to add the same contract cross-org

[0x0elliot]

#104 too sleepy but suspicious i broke something