Maybe this will help---my EZ pass was issued by the PA Turnpike maybe 10 years ago, maybe more.  At the time I lived in MD and they decided to charge a fee so I dropped the MD one and got the Turnpike one which at the time was free.  I now live in NC and have used this pass all over the country without ever a problem.  I transfer it from one vehicle to another often, cars, pick ups, motorhome.  With both the trucks and the motorhome I often tow a 32ft enclosed car trailer w/3 axels so at times I have had 6 axels but usually 5 and used the EZ pass all over without a problem.  I think the original registration was to one of our long gone cars.  I don't ask questions and neither have they.  Hope this helps.