Yes, and the standout is Dulux Tuscan Glade 3 (LRV 45.6). At ΔE 2.4 from Little Greene Aquamarine, that's a very close match — anything under 2.5 is genuinely hard to spot once it's on the wall and dry. For a softer, mid-tone green like Aquamarine, you'll get away with it easily, and you're paying Dulux trade prices rather than Little Greene's premium.
The two other options in the frame are further off. Crown Craft Fair (LRV 39.6) sits at ΔE 4.9 — that's a noticeable drift, reading darker and a touch more muted than the original. COAT Home Grown (LRV 53.4) comes in at ΔE 4.7, but it pulls the other way: lighter and fresher. Neither is a true match, so treat them as relatives rather than dupes.
Here's the honest bit, though. Little Greene's pigment load and depth of colour are part of what you pay for. Aquamarine has a particular chalky-yet-rich quality, and Dulux Tuscan Glade 3 gets remarkably close on hue but the finish character can differ — Dulux's standard emulsions are flatter and less velvety than Little Greene Intelligent Matt. If the wall's in a room where you live with the light all day, that finish difference matters more than the 2.4 ΔE.
My advice: order a sample pot of Tuscan Glade 3 and brush it out next to an Aquamarine sample on the actual wall, north light and evening light both. If you can't tell them apart — and at ΔE 2.4 most people can't — you've saved yourself a tidy sum. If you can, and the difference bothers you, that's exactly the £20-a-litre premium Little Greene charges for, and only you can decide if it's worth it. For most jobs, the Dulux is the sensible call.