Someone might find this useful for speedrunning. I found that sometimes I can get double melee damage at the beginning of the dual bogie fight. This is on God Hard mode,

You can see that first hit does double damage. I use that sliding melee strike with the rocket launcher, and it seems by triggering the melee input a little early it increases the chance of double damage. I still cant trigger it consistantly but I noticed this through hours of grinding this fight. I was never speedrunning this game but Ive never once heard this mentioned. Maybe its not a glitch and something else. Any ideas? Let me know if you find it useful.