The black roan appaloosa mule was all over the place during his time with his regular release in the Stablemate Assortment as #5609 Mule (1998-02) and then as part of a play set in the #59197 Stablemates Little Red Stable Set (1999-2001).
The other look-alikes fall in the "yellow" spectrum with two duns and a roan. The first model, on the top-left, is from the #5909 Farm Animals Play Set (2005-08) and is a lovely orangey chestnut dun. The mane and tail are a darker tan than the body and the muzzle and ears are shaded in the same colour. The legs are pale and the hooves are dark grey. The model should have eye-whites and white teeth with a rather eye-catching black line defining the gap between the upper and lower teeth.
On the upper-right is the other chestnut dun model. From the Just About Horses #790798 Special Edition Stablemates Gift Set (1998), this model is more of a creamy tan with chocolate mane, tail, legs, and head, leg barring, and a shoulder stripe in addition to the dorsal strip. The teeth, hooves and eyes are black. This is the only G2 Mule to be produced in old plastic.
Though the final model is a roan, not a dun, it is still similar enough to the others to cause confusion to those less familiar with the Mule releases. The bay roan Mule from the Mid-States Distributing/Rural King #9962502 Deluxe Farm Pocket Barn (2007) is more of a smokey grey-brown in body colour with darker legs and head and black mane and tail. The hooves are a slate grey and the model has eye-whites, a lighter shaded muzzle, and white teeth with a pink tongue.