Multiple masternodes under the same wallet address aren't working

### Describe the issue

When multiple masternode outputs are sent to the same address; they will run, however rewards aren't paid at the frequency they should be. It seems to earn rewards at the same rate if there was only one masternode on that ip address.

### Can you reliably reproduce the issue?
#### If so, please list the steps to reproduce below:
1. Send 10000 coins to the same address as another masternode
2. Setup the masternode and observe the rewards.

### Expected behavior
It should only care about separate outputs; and not separate wallets. It's likely this is a consensus issue, so therefore won't be able to be fixed until the next consensus change.

### Actual behavior
Ya get ripped off.