Sony FD Trinitron WEGA KV-32HS20 Operating Instructions Manual page 22

Installing the TV
To use Twin View with the cable box
Turn on the VCR. (The VCR's tuner is used as one of the Twin
View picture sources; if you do not turn on the VCR, the Twin
View will not work.) Use the remote control's IV/VIDEO button to
set the Twin View output to VIDEO 1. Change one Twin View
channel by changing channels on the cable box.
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