Yes, and you've got a cracking option. Dulux Sunflower Symphony 2 sits at ΔE 0.7 from Little Greene Middle Buff — that's well under 1, which means the difference is imperceptible to the eye. Side by side on a wall you genuinely would not be able to tell them apart. With an LRV of 22.1, it carries the same deep, mustardy-buff warmth that makes Middle Buff such a lovely colour for hallways, dining rooms and snugs. If money's the deciding factor, this is your answer — same look, lower price per litre.
The usual caveat applies: a tight ΔE match gets you the colour, but not necessarily the *finish*. Little Greene's paints have a particular depth and chalkiness, especially in their Intelligent Matt and Absolute Matt, that comes from how they're formulated. Dulux's standard emulsions are perfectly good paint, but the surface texture and the way light moves across it can read a touch flatter. For most rooms that's a non-issue — for a feature wall you're going to study closely, it's worth a tester pot first.
Worth a mention: COAT Heir Brush comes in at ΔE 3.9 (LRV 21.9). Not as tight a match, but COAT is a genuinely good eco-credentialled paint with low VOCs and a self-priming formula, so if sustainability matters to you it's a sensible middle ground.
I'd steer you away from Crown Market Day here — at ΔE 11.5 it's a noticeably different colour, more of a separate shade than a dupe. Don't let the name or the swatch fool you; that gap is visible.
Practical advice: order a tester of Sunflower Symphony 2, paint two coats on lining paper and prop it against your Middle Buff swatch in both daylight and evening lamplight. If you're happy, you've saved yourself a tidy sum. Buff tones can shift warmer under tungsten bulbs, so always check it in the actual light of the room before you commit.