New modems already registered.

I bought a brand new modem from Target and called Comcast to activate.  The tech told me the new modem was already registered to another Comcast customer.  

That same evening, I bought a second brand new modem from Walmart.  A different tech told me that the second unit was already registered to a Comcast customer.  

She then realized that the odds that I bought two new units in new packaging from two different reputable retailers — and that they were both previosuly registered to other Comcast customers — was unlikely.  She put me on hold and I got transferred to another tech who told me that it was the manufacturer’s problem and he was certain the problem was not a Comcast issue. 

I notice this is not the first problem of this nature on this forum.  Is this to push people to use rental units?