Honest answer, mate: Dulux doesn't have a real match for Little Greene Mid Azure Green. The closest two in the Dulux range are Heathland at ΔE 7.8 (LRV 3.8) and Pine Needle at ΔE 8.5 (LRV 5.6) — and a ΔE that high means you'll see the difference plainly on the wall, side by side or not. For context, anything under ΔE 2.5 reads as a very close match and under 1 is imperceptible. We're nowhere near that here.
The trouble is the character of the colour. Mid Azure Green is that rich, slightly blue-leaning teal-green — there's a depth and a cool azure pull to it that the Dulux options just don't replicate. Both Heathland and Pine Needle land in deep green territory but they sit greener and a touch heathery/dusty, so you lose the azure tilt that makes the original sing. As substitutes they'd read as a different colour entirely, not a stand-in.
So my advice: if it's Mid Azure Green you've fallen for, buy Mid Azure Green. Little Greene's Intelligent Matt or Absolute Matt holds that depth of colour beautifully, and on a teal this saturated the pigment quality genuinely shows — cheaper trade emulsions tend to go flat and patchy on the deep tones.
If the reason you're after a Dulux equivalent is purely budget or trade availability, I'd rather you picked a deep teal that Dulux actually does well and own that choice, than accept a poor match and feel let down once it's up. Order a sample pot of the Little Greene first, paint two coats on a big bit of lining paper, and live with it for a couple of days before you commit. Deep teals shift a lot between daylight and lamplight — you want to see it doing both before the tin's open for real.