The numbers are arbitrary.  It's by the timings you can tell which is which.  Look at the BIOS for a card that only supports Elpida to find the standard Elpida timings.  Compare that to the timings in your BIOS, and if one of the type 01 timings matches, then you know it is Elpida.  Same thing for Hynix.

Although I haven't tried it yet, I suspect the two (Elpida/Hynix straps) are interchangeable.  I have tried changing a few of the individual timing entries with the goal of making fully custom straps, but it's too much work for too little benefit to try to figure out all the timing values.  GDDR5 doesn't just have RAS/CAS timings, it has things like the four activate window (tFAW), 32 activate window, and more.
If I could get my hands on an AMD BIOS developer's guide, it would be much easier...