MARC ticket/paper stock question

This past Thursday (12/21), I took my first-ever rides on the MARC trains as part of a day trip to Washington. (I drove from Harrisburg to Timonium, used the Baltimore light rail from Timonium to Penn Station, and the MARC from Penn Station to Union Station. On the way back, I used the Camden Line between Union Station and Camden Station.) One thing that was interesting and surprising to me was that at both Penn Station and Union Station, the ticketing was done through Amtrak, or more specifically the MARC tickets I bought were printed on Amtrak paper stock. My question is what kind of paper stock does the MARC have at non-Amtrak stations, Amtrak stations without ticket offices or machines (but do have MARC facilities), or MARC stations that don't have ticket offices or machines? I like to save many of my rail tickets if I can, and it was a disappointment that my MARC ticket stubs look identical to Amtrak ticket stubs (and I have a number of Amtrak stubs).

Incidentally, on the Penn Line portion of the trip I rode in a double-decker car, something I'd never done before (I was on the top level). Also, my initial impression of the landscape along the Penn Line was that it quite similar to the portion of NEC further north between Trenton and New Brunswick in central New Jersey (which I only rode on for the first time about 1 1/2 months ago) - surprisingly rural in many locations and lots of woods. Finally, I also checked out Alexandria Amtrak/VRE station (among other things in the DC area that are walkable from the Metro); that's a nice, little station, and I like its location practically next to the impressive Masonic Washington Memorial. I had the added bonus of seeing an Amtrak train, I'd guess a Regional, leaving the Alexandria station at the same time my DC Metro Yellow Line train was arriving at the adjacent King Street Metro Station.

Chip,

"Traditional" MARC tickets are printed on a slightly more squarish size ticket, with navy and orange striping. I'd believe that you could acquire these at Baltimore Camden Station. However, at Baltimore Penn, Washington Union, and BWI, its going to be Amtrak stock.

You can also get them through the mail in MARC format not Amtrak last time I ordered.