I would suspect a malfunctioning remote that's sending something other than the button you're pressing. The most common reason for channels getting installed "on their own" is because people are using one of the Roku screensavers with little ads floating by. Pressing Play/Pause on the remote will install whatever's being advertised, but Home shouldn't do it.
Can you try using the mobile app as a remote to see if the problem goes away?
Roku Mobile App - Free for iOS® or Android™ | Roku
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