Kenneth,
I have a friend, Joe Trevithick, who knows this stuff like the back of his hand. He was kind enough to send me this reply to your inquiry:
Ray,
"The alpha-numeric bit (like XM18) is only one component of the designation in the Army's nomenclature system. The alpha-numeric is not a complete designation in of itself and requires the full descriptive text string to avoid the confusion you point out. You can find a full description of the specifics of the system here: www.designation-systems.net/.../miscsystems.html
In short, these designations are not in fact repeated. The full designations in this case are:
- ARMAMENT SUBSYSTEM, HELICOPTER, 2.75-INCH ROCKET LAUNCHER: XM3
- DETECTOR, CONCEALED PERSONNEL, AIRCRAFT MOUNTED: XM3
- ARMAMENT POD, AIRCRAFT, 7.62-MM MACHINE GUN: XM18
- DISPENSER, AIRCRAFT: XM18
Also, the XM18 aircraft dispenser is just the US Army designation for what the Air Force designated the SUU-14/A. The dispensers themselves should be essentially identical. Here is a picture:
I think that should help clear things up. Happy to help.
Joe