Just cut one separate it from the other yellow wire and connect it to the red one.
do run test without fully install the stereo.(save you the hassle removing if things not right)
turn ignition ON and see if the stereo power up, pre-set a radio channel and turn ignition OFF
turn ignition ON again and check if the radio setting still there
If it's station need setting again then you need to swap both yellow wire pin in their place.
both yellow wire supplying power - just checking which is constant feed
re-test again on the station pre-set (if setting still there means you got the right connection)
some final tidy up on the cable, install new stereo unit and you good to go :D