Cannot replace a plugin with the same plugin (with different settings)

**Describe the bug**
I've added the plugin `Blockchain Interaction` to https://rinkeby.alchemy.do/dao/0x6ec530f0d9dddc0acb1752fe852d0ef54d895628 then removed it.

Now I can't add it again: It is missing in the list of plugins to add in "Add plugin".

**To Reproduce**
Steps to reproduce the behavior:
1. Vote to add a plugin.
2. Vote to remove a plugin.
3. Try to add it again.
4. It is missing in the list.

Also, there is no way to replace a plugin with the same plugin (but different settings) without removing it first.

**Alchemy Version Number**
2.0.0