“A configuration with this name already exists” error in eclipse run configurations

I synced mercurial project, and tried to setup run configurations.

I found the name has (1) attached, and I tried to remove it.

However, I got A configuration with this name already exists error. I checked other configurations, but there was no duplication of Name Equivalence Checker.

How can I find the existing configuration to remove it?

Answer

uncheck the filter: Filter Deleted/Unavailable Projects