A FOSS alternative called Shenidam of the commercial tool named DualEyes is available.

It allows an audio track that has been recorded with an external portable recording system to be synced up with a video that has been captured with a digital camera and that also has a sound track but of lesser quality.

Project homepage: http://shenidam.org/
Getting started with build instructions: http://shenidam.org/node/3

That would be cool to have it integrated into kdenlive!

Alphazo