on MacOS image is opened twice the first time
Mac specific bug, it exists since ever and persists. I can reproduce it on Mac 10.5, 10.6, 10.7, no newer systems at hand.
If an image is opened by starting GIMP (e.g. open in GIMP through the file context menu in the finder) and GIMP is not running, the same image is opened twice. in Gimp 2.10 two tabs open and two times options are choosen (e.g. color profile conversion).
If, instead, GIMP is already running, it does not happen.