How to use Stretch Marker without stretching sound out of shape?

Please see attachments. I was trying to sync up a tambourine loop to my song, and I noticed that moving one beat will cause the previous one to stretch longer, resulting on an echoed loooong sound. How do I perform this function and not have that happen? Thanks.

Or why stretch at all? For a percussion track like that you could use "Dynamic Split" and "Quantize items to grid". Check out this vid...

Below I have "Insert Marker" on Alt+Click & "Move Pair" on the CTL modifier. Like Run says, protect the other audio with outside markers and only stretch digital silence when possible. It's a really easy timing adjustment now. The audio moving isn't being stretched at all. The only thing that might cause a minor issue with tambs or something is the 10ms gap thing, if you click too close to another marker. The workflow is very, very similar to S1's bend workflow except for Reaper's mouse modifiers...

I'm now trying to put markers on both sides of a beat and move them and it's still stretching, so what else do I need to make it work like in the above illustration?