I'm familiar with US/Canadian Panasonic models, not the EB models from the UK. I don't know what a "decoder tag" is or does.
Since US/Canadian Panasonic DVD recorders do not modulate the RF output--the RF output only passes through the RF input signal to the RF output--the DVD recorder generated signals are not found on the RF output. If the RF output is the connection you made to the different TV try another connectivity arrangement.
Panasonic VHS/DVD combo recorders have an unmodulated RF output upon power-up but switch to a modulated RF output by pressing the SCHEDULE button or when playing or recording a videotape or DVD.