Okay this this is one of those kidnapped/help out a settler type mission we've probably gotten before, but I keep getting a chain of them each time I go to Sanctuary.

First off, every time I travel to Sanctuary there is a settler there waiting to start the mission. If i take it, then I complete it and get the XP but the same settler will re=appear later again with the same mission. If I kill the bugged settler it will say I failed the mission but then auto-start it again and I have to go speak to Preston GRAVY to repeat the whole process...

When another settler shows up (and they will) I could just ignore them or deny to help them (P. Gravy will not like that), but they just follow me everywhere and it's annoying -.- any fixes?

I'm on Xbox One if that matters.

That's not really a bug, per se. It's just a SUPER annoying consequence of the radiant quest system for the Minutemen.

You slow them down by completing the assignment but NOT turning it in. That buys you a few days before they will autocomplete (successfully) and "free up" a slot for another radiant mission. You can also just avoid Preston and/or tell the people "No" when they ask if you're from the Minutemen. Finally, for kidnappings, you can just pay the ransom.