What you were doing when the issue happened
Typing in the RStudio for OS X script editor panel
Select text
Press COMMAND-C to copy or COMMAND-X to cut
2-3 out of 4 times the selected text APPENDS to the clipboard rather than replacing it, as if one had used Alfred's COMMAND-C COMMAND-C double tap.
Whether you were able to replicate it a second time by performing the same action
Happens 100% of the time. Have had to add RStudio to the ignore apps list for the clipboard feature to be able to use Rstudio reliably --- but that means I can't use my favorite utility with my most freq