Routines other than the first one is just used to fix bugs of it. If the double wild battle doesn't happen, you should see if you've inserted the first routine correctly and do all the byte changes in the comments in the routine.
I had inserted all the routines in my hack and I'm kind of glad that it doesn't crash the game or make any unwanted errors, well my problem is even though I set the percentage value of double wild pokemon appearance to 64, which is 100%, nothing happens. The grass ID is the default, 0xD, and all are fine.
Do you have any idea why setting it to 64 doesn't create a 100% double wild pokemon appearance?