Seeing double devices in SmartThings - one as "placeholder"
I've had 2 Slim Edition plugs (from KP100KIT) and 1 HS105 running very successfully for about 6 months. I operate them via Alexa (Echo Dot) and my SmartThings Hub. I recently added a HS107 "double plug" - I've installed it, it appears in my device lists in the KASA app, Alexa app, and in SmartThings, but am currently not using it yet. I installed via the KASA app - all look good in that app. I "found new device" in Alexa - that worked. I also added it in SmartThings Hub - this is where something strange (to me) happened. In SmartThings. I see two entries for each of my KP100 plugs and HS105 - I can turn them on-and-off, but one of the "duplicate" entries shows "Type" of "Placeholder". The "placeholder" entries for the KP100, HS105, and HS107 all show a "link" such as TP-LINK|:HS105(US)|:800629655A9580EEB1067700CE4E71F71A530FF3.
I don't know what to do to get rid of the double devices - what is this "placeholder" trying to tell me? Should I remove all the devices and re-discover them? I'd appreciate some insight and suggestions. Thanks.