I think the acronym thing is related but a separate phenomenon. My guess would be that speakers intuitively think the acronym isn't easily understandable so they add an extra word to clarify it, intentionally or unintentionally duplicating one of the actual words in the acronym.
"pont bridge" sounds like the exact phenomenon though. Does it have a more specific meaning that "bridge"?
But also in Canada some uni-lingual English people may say "pont bridge" not knowing pont is bridge in French. Maybe uni-lingual French say the same?