at least as early as 1985/6 JA sounds have been mixing tunes on one riddim anyway... mixing different riddims since late 80's/early 90's then....
so sound system history has plenty of people mixing reggae.
Without disrespect to anyone I used to go sound dance in Dublin where the selectors mixed off two decks, but in a one deck style, if you know what I mean. Play the full tune to the end, let the silence descend, maybe used the siren or have the mc say something and then go into the next tune eventually.
This style used to bore me to tears. Towards the end I found it unbearable. Selector has got to keep the vibes in the dance going. At the very least they should be able to drop tunes in at the end of one, preferably they will do it at an appropriate time in one tune, or mix proper like Fatha Twice.
Reggae mixing isn't like techno.... we're not talking about having big 60 second overlaps of one tune on top of another with eq etc.... no what it's all about is keeping the flow of the dance going... next tune mix in on time and keeps the beat going, dancers keep dancing, girls keep bubbling....
To me the one turntable style KILLS the vibes.
But that is me, and has often been pointed out there are very definitely 2 separate sound system traditions/cultures, certainly in the UK. There is no reason why we all can't respect what each other does and just agree to differ.
What gets to me is the high-brow attitude that if you mix (which to me is done to please the crowd, build a vibe) you are some sort of egotist who is placing yourself above the artist/musicians on record. Or the attitude that you are not following the real sound system tradition or whatever.
sorry for the rant