I should note I have neither pony, but these are how I perceive it.
I don't think there are any other ponies with a colour close to Agua Limone. Minty is much paler, and a very different shade. Agua Limone is really quite vibrant.
Magenta haired Minty probably isn't exactly the same colour as HK Lemondrop, but from looks alone, I would say she's close enough to make a credible custom