You may be talking about pronounce perhaps.
There is a difference hear here:http://www.macmillandictionary.com/dict ... tish/mango
ˈmæŋɡəʊhttp://www.macmillandictionary.com/dict ... h/mangle_1
The first is close to "mangol" (in Portuguese, "gol" como o gol de futebol) the second closer to "mãe-gol" (said in a quick way). But, you can see it from the listening, the link I provided. It´s a better way to learn.
On the topic of "the word in action", I would say that "mangle" would be rarer in a sentence than "mangled" http://howjsay.com/pronunciation-of-mangled
You would deduce from the context, because the meaning of "mangle" is that of "destroy/mutilate" etc. So, from a given context the probability of one being used in such a way to be mistaken for the other.
Example: "The guy with the mangled arm and shoulder had a gun."
After having something listening experience you will know that a guy can´t have an arm in the shape of a mango! Let alone hold a gun with it...
I mean with time your ear get used to the sound and the structure as well, sort of.