Originally posted by: Curium
I don't think Dual was really inferior, they just had different intentions. For example Dual was the only one of the original Gundams that could use weapons from any of the others. All the beam weapons were hard coded to only work with the Gundam they came with, except Dual was programmed to get around that. Also Dual was supposed to be equipped with a Large Bazooka, but that was taken by the Gold Frame Astray. Here is a segment from MAHQ:

"Rondo escapes from Heliopolis using a large bazooka designed for the GAT-X102 Duel Gundam, but the Gold Frame's right arm is damaged because it is not properly calibrated for use with the bazooka. Rondo jettisons the damaged arm".
I think I remember reading that Duel was the first one and then all the other GAT suits were based on it.
My memory might not be what it used to, though.