UV's automatically stick together
 

The Uv's automatically stick together when they are placed close to each other.

Below is an example.


I select two UV's of the left projection.
https://lh5.googleusercontent.com/-2...2AQ/s640/1.png

It selects the right objects UV's, but the manipulator tool shows that the left object is selected and the right UV's are orange.
https://lh6.googleusercontent.com/-4...JHs/s640/2.png

They move together.
https://lh4.googleusercontent.com/-d...vMg/s640/3.png

I didn't change any settings(that I know of) since I created UV's for another object.

Not sure what it was. Just returned Maya to default settings.

You turned on soft selection. Check out the FAQ entry on it.