In this quiz on Yle's website I met the nice word "murremestari": https://yle.fi/a/74-20058169
Obviously this means one who masters dialects, but in that meaning I pronounce it as "murremmestari".
An amusing alternative is pronounce it as written, which I then hear as "Murre-mestari", with "Murre" being a dog name.
The first pronunciation also seems to have more weight on the double-r, but I am not quite sure.
I am no linguist, but this change in how I interpret the word is kind of fascinating. What is going on here?