I have run into similar situations. What I have noticed is that the files in question normaly have something just a little different.

For example the file size may be different or the title may have an extra space in it.

If the file is in d/l screen it should resume automaticaly if you find a source. If it is in the incomplete folder you can highlight the file and click resume one time, and this should move it back to the d/l window. Do not click resume more than once as this creates a hardship on your resources and the G network

I normally d/l the one that has the best speed. Then delete the other out of the incomplete folder.