Geraint Lewis’ Pontypridd side were the winners in the return fixture last weekend but the English Championship side evened things up on Saturday.
The result means the two sides are now level on points at the top of Pool 2 with qualification for the quarter finals likely to go down to the final round of matches.
The visitors had actually led 14-12 at the break with Craig Locke and Simon Humberstone crossing for Pontypridd and the latter adding a pair of conversions.
A penalty score for the opening try of the day and a Mark Bright effort had been highlights for Scottish in a first half which saw each side receive a yellow card.
A Matthew Nuthall break was a good start to the second period for Pontypridd but with the game being played at a frantic pace, a yellow card for young back Aled Summerhill proved key. Bright claimed his second try with winger Miles Mantella adding a converted score.
Thomas Young crossed for Pontypridd’s third try but the defending Principality Premiership champions had to settle for a losing bonus point.
At Pandy Park, Cross Keys scored 14 points but it was not enough to stop them going down to defeat against Leinster A.
The Irish side were 14-30 winners at the home of the Gwent outfit but Keys boss Greg Woods believes his side can still qualify for the quarter finals.
“Leinster were really strong, I thought their driving lineout was superb and they had us under the pump for a lot of the game,” he said.
“But we played well in patches. It was the try they scored just after half time that really killed us.
“I’m pleased with the way we’ve performed over the last two weeks against a very powerful side – we have been very competitive and we’ve shown the Premiership in a good light.”
Woods added: “We aren’t out of this tournament yet but we do need to get the maximum 10 points from our next two games.
“I thought players like James Cordy-Redden, Leon Andrews, Scott Matthews, Ieuan Jones and Jevon Groves carried well – we stuck at it and never gave up.”
In the north of England, Llanelli put up a credible showing before going down to a 20-15 defeat to Rotherham Titans. It was a second loss to the English side in a week and leaves Kev George’s side bottom of Pool 3 with two matches to go.
A penalty from Scarlets man Steve Shingler was Llanelli’s only effort in the first 40 minutes but three more penalties at the start of the second half saw them draw to within a point. Rotherham then re-established an advantage and although Dion Jones kicked a late long-range effort, they ended up five points short.
Aberavon went down to a 72-0 defeat to Leeds Carnegie.
