Try one of these HDMI splitters that are more or less openly advertised as "HDCP strippers" on Amazon.

I think multiviewer might have been a synonym for that.

I wonder if the chips on these dummy plugs are powerful enough to hack in HDCP support though.

The dummy plugs are literally just a 256-byte eeprom hooked to the I2C lines, there's nothing else inside the shell.

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