I have to confess a major mistake!  The "old" RL19 I thought I was using wasn't RL19 at all!  Back in the late 80s I loaded a bunch of 30-06 with both RL19 and IMR4831.  They were my fireball producing loads for my Madsen bolt action rifle.  I kept them in different ammocans, and when I pulled them down, I kept the powder separated.  RL19 went into a RL19 can I had, the IMR4831 sat in a loosely covered and unmarked container on my bench.  Although I had a vague memory of the IMR4831, I forgot those long ago loads and when I was packing up to move, assumed the powder was RL19.  Now I know why it looked so different from the new!  Thankfully, it was a mistake in the more lenient direction and wasn't a faster powder.  I don't have any IMR4831 at present, but the burn rate tells me more than the appearance would.