Warnings cap per entity should be applied for unique warnings only

[yaelmi3]

Currently we're capping the number of recorded warnings per entity to 50, but do not distinguish between repeated warnings and unique warnings. This might cause situation where unique warnings will be omitted from the display. For example:

    for _ in range(50):
        warnings.warn("Hi")
    warnings.warn("Bye")

will result in:

and "Bye" will be omitted from the display