Yes, and you've got a genuinely good option here. Dulux Smokey Slate is the standout — it lands at ΔE 2.1 from Down Pipe, which is well inside the "very close" threshold. On a finished wall you'd struggle to tell them apart, and Smokey Slate carries an LRV of 12.3 against Down Pipe's deep, leaden grey, so it reads with the same sombre, slatey weight that makes Down Pipe so popular.
If you'd rather shop elsewhere, Crown Smokey Grey is the next best at ΔE 2.5 (LRV 11.3) — slightly deeper and just nudging the edge of what counts as a very close match, but still a faithful stand-in for a third of the price.
COAT The Coal Drop comes up at ΔE 3.5 (LRV 14). That's a noticeable step away — a touch lighter and a hair warmer — so I wouldn't sell it as a true Down Pipe dupe. But if you fancy that family of dark architectural greys and like COAT's quick-dry, low-VOC formula, it's a lovely colour in its own right. Just don't expect it to disappear next to the original.
Now the bit nobody mentions: Down Pipe's reputation isn't only about the hue. F&B's Estate Emulsion has a particular chalky, light-eating flatness that the cheaper trade emulsions don't fully replicate — Dulux and Crown finishes sit a little flatter or a little more plasticky depending on the sheen you pick. If that ultra-matt depth matters to you on a feature wall, that's where you're paying the F&B premium.
My advice: get a Smokey Slate tester and a Down Pipe tester, paint them side by side on a bit of lining paper, and move it round the room over a day. North light is where greys like this misbehave. Nine times out of ten you'll happily pocket the saving and go Dulux — and on woodwork or a hallway, you'll never miss the difference.