Thank you for reporting this problem. It has already been reported in this forum thread.
The double-paste issue seems to happen:
(1) Only on Mac (not on PC).
(2) Only when pasting via keyboard (not via mouse context menu).
(3) Only under Adobe AIR v14.0 (not previous versions).
I have notified the developers of this problem but it looks like there is, indeed, a problem with pasting via keyboard in Adobe AIR v14.0. Please see these links for further details:
https://forums.adobe.com/thread/1495749
https://bugbase.adobe.com/index.cfm?eve … id=3775354
In the meantime, workarounds would be to either:
(1) Paste the text via mouse context menu.
(2) Type the text into the input field.
(3) Paste the text via keyboard and manually delete the duplicate entry.
(4) Revert to a previous version of Adobe AIR (not necessary if using #1, #2 or #3 above). Previous versions of Adobe AIR can be downloaded from this web page.