Thanks to WizenedEE for catching my mistake there. I've corrected it, getting the results 1 1 27 and 1 1 148 respectively.
Sorry for not being very clear, I should clarify my question further. I am trying to use PROGMEM to store my data, and this is a test program I wrote to see if the data was being transferred and subsequently read back correctly. The first two print commands certainly worked out as expected, returning a decimal value of 1 for the hexadecimal value of 0x01. The third print statement however returns 27 or 148 when depending on whether I used "&testdata" or "testdata" in the pgm_read_byte command.
My question is, does this show that the data is somehow being corrupted along the way? How can I know if the data I want written is actually being written correctly?