Question

Why does each sip2 server create 2 connections to Oracle -- with two Oracle processes?

Answer

Not only sip2, but almost every Aleph process opens two oracle connections. See, for example, ue_01:  

  ps -ef | grep ue_01_a | grep USM01  

shows:

  aleph 27795 1 0 14:55 pts/21 00:00:01 /exlibris/aleph/a22_2/aleph/exe/rts32 ue_01_a USM01.a22_2 

Then "ps -ef | grep 27795" gives: 

  oracle 27801 27795 0 14:55 ? 00:00:00 oraclealeph221 (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq))) 
  oracle 27802 27795 0 14:55 ? 00:00:00 oraclealeph221 (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq))) 

This is because many processes read/update the z52 (seen in util g/2), and it must be updated on the spot, so it must have a special connection.