Duplicate popups when adding a custom ParameterInfoHandler

I'd like to override the default parameter info UI for Python files.

For this, I've experimenting with a custom ParameterInfoHandler implementation. This isn't using the default HintManager / yellow bubble popups.

The implementation is called, but the custom UI is displayed in addition to the default popup so that both popups are shown. I think that it's caused by this: https://github.com/JetBrains/intellij-community/blob/master/platform/lang-impl/src/com/intellij/codeInsight/hint/ShowParameterInfoHandler.java#L115 .
Is this a bug or intentional?

Is there a guideline how ParameterInfoHandler should be used?

Notably, the implementation when a lookup is present is only using the first handler and thus different to the implementation when no lookup is shown: https://github.com/JetBrains/intellij-community/blob/master/platform/lang-impl/src/com/intellij/codeInsight/hint/ShowParameterInfoHandler.java#L103