There used be 1vs1 on primedice.. but no more.
AFAIK they removed the pvp game because there were some players exploit it whenever there was happy hours. Something like playing pvp with their own alts to collect as many as btc.
But I could be wrong on this.
Yes, you are right. That is exactly the reason why they removed the pvp from dice gambling sites. The minimum tip is 50k sats, so thats not easy to make the 50k from faucet and then tip your alt with it, but with pvp you could transfer any amount to your alt immediately and then claim from the faucet again.