If the feature merger isn't merging (on the original value, compared to the copy/pasted POINT (154791.869730325 463171.926750512)), then they're not the same value. They may look the same, but something about it has changed. That, or it's the wrong xml value.

You could try a string searcher/string replacer, to see if there's any character which isn't meant to be. Regex like [^[:alnum:]] will find anything which isn't alphanumeric, or [^[:alnum:] .()] to search for or replace anything you wouldn't expect to be there.

Also, turns out you can safely add a space or enter at the end of a wkt and the geometry replacer still works fine.

I am sure it's the right xml-value. I tried the stringsearcher, but I still can not find a difference between the two attributes.

https://repository.overheid.nl/sru?query=c.product-area==%22lokalebekendmakingen%22%20AND%20w.locatiepunt%20within/rijksdriehoek%20%22155000%20463000%200.3000%22

Then: XML fragmenter on "geometrie".

The process works for me (XML Fragmenter followed by geometry replacer) in an older version of FME