It seems I just cannot win with the MIDI bugs in SONAR... I've tried this with normal clips and Groove clips and the following happens (note, they're not linked clips)
 
When I move a clip or drag-copy, the other clips in the lane jumps around insanely as seen in the GIF:
 

That's pretty weird. Sure looks like a bug.
 
Unfortunately, I am so far unable to duplicate that behavior here. These are just normal MIDI clips? The other clips appear to be copies of the one you're moving, is that correct? If so, were they copied via ctl-drag or another method?
 
Can you duplicate the problem with a new project and a single MIDI track, or is it specific to this particular project?

Created a brand new project, and it happens with copy-and-paste clips as well as drag-copy clips...
 
I think my SONAR needs a fresh install

My guess is Preferences > Customization > Editing "What to do with existing material:" is set to "Slide Over Old to Make Room." If this is the case, change the value to one of the other two options. This is a very old bug.

scook
My guess is Preferences > Customization > Editing "What to do with existing material:" is set to "Slide Over Old to Make Room." If this is the case, change the value to one of the other two options. This is a very old bug.

THANK :)
That solved my problem :)