fitbit/mfp logging exercise

JSAV513

I typically walk with my pup in the mornings and log that info to mfp and it will give me an estimated cal burn.
I have a fitbit and that has a different, more accurate cal burn ( i hope!). The other morning I wasn't able to log my walk to mfp before my fitbit synced to mfp and it gave me an adjustment of 200 cal ... Question is - Did mfp know I worked out because my fitbit was in activity mode?
Should I just let it update my walks and not log them, but always put it in activity mode when I do walk? Thanks in advance for your replies.