Fitbit and Endomodo

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I use a fitbit and my daily exercise is walking, should I also track my walking with Endomondo and let it update the calories to MFP? or will this double track my exercise?

On another note (I think) - I have not actually used Endomondo at all yet to track any exercise.
I have got the app on my phone, but I have never used it or paired it with my HRMonitor.

Every so often I find that there is an Endomondo exercise adjustment which appears in my exercise log on MFP, sometimes it says I have done eg 15mins dog walking....other times it may say 170mins dog walking, but I have never actually used it to track any exercise and sometimes it appears when I haven't even done any exercise at all... it this something to do with the fitbit syncing my exercise?

Sorry if this is something stupid and I should already know the answer!