How do I quickly move vertices to the same location? I can snap cursor to vertice and then move the other one to the cursor but it takes a very long time.
You could use the Stitch tool to stitch together the vertices along each edge.
Select two edges that you want to join then open the UV menu and choose the Stich option. (shortcut key = V ).
At the bottom of the UV editor view you will see a list of the Stich options. Use the Snap option: S key.
Left mouse button the validate Stich.
Select the other two edges, then V followed by S again.
Note that if you don’t want to move the vertices of the lower UV island you may have to use the Switch Island option: Shortcut key = I .
Left mouse button to validate.
If the vertices you are wanting to move to the same location in the UV space are not joined in the actual mesh then the stitch tool will not work.
Then you will have to use the snap tool: Enable Snap tool and and snap to Vertex option.
Then select a vertex and drag it towards the verticex you want it to snap to. Unless you have hundreds to do this should not take very long :).