There should be no reason that would prevent you from selling them.
I can only imagine that the store recorded your receivers within the PRISM system, which is Express Vu's database.
If this is the case, call Express Vu, explain that you bought them, they may require the R00 #'s from them for confirmation, then tell them you are selling them on and give a name, they should then record that data and give you the green light.
The 9200's will not become fully obsolete for probably a decade or more, they will however stop showing HD programming but not for at least the next 2 years, after which you will have 2 very good Dual Tuner SD PVR's.