Twin sat / twin tuners have two cables so yiu can watch and record more than one channel at a time. Each cable gives you the whole sat channel.

I would avoid the solo and duo as both quite old and dated.

Bang for bucks the HD51 at 228 for a twin tuner is not bad and future proof as it's a 4K box but if you do not have a 4K TV and won't for couple of years, look at some of the other cheaper twin tuners or single ones if you don't want twin tuners

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