Hmm, I'm not sure. For one thing, that's the *only* .HRC file in magic.lgp. It does have plenty of .P and .Pxx files.Here's a dump of deathlv5.hrc from Notepad:
:HEADER_BLOCK 2
:SKELETON deathlv5_sk
:BONES 3
head
root
45.797066
1 head
none
root
3.3178074
0
jaw
none
17.573845
1 jaw
It looks like a typical .HRC file. However, your thinking about the two using the same format is probably not too far off. There's a lot of formats in magic.lgp we don't know. It contains:
-.a00: 79 files
-.anm: 1 file
-.b: 23 files
-.d: 36 files
-.geo: 2 files
-.hrc: 1 file
-.lmd: 12 files
-.p: 582 files
-.pxx (XX is a number): 1063 files
-.rsd: 618 files
-.s: 359 files
-.script: 1 file
-.shp: 2 files
-.tex: 670 files
.tXX (XX is a number): 24 files
Oh, and I discovered that there are no "magic" files. They are all .p10 (Pxx) files.
.a00 files *could* be the same format as .A files. Same thing with the .ANM file. B., .D, .GEO, .LMD, .S, .SHP, and .tXX we don't know. As for the .HRC, .pXX, and .SCRIPT files, I'm not sure why they're there... yet. I'm guessing the .S files could stand for "spell".