When I look at 'top', the spamd processes are not sharing enough memory

Here's a sample output from "top" viewing two spamd processes:

  PID USER      PR  NI CODE  VIRT  RES  SHR nDRT %CPU %MEM   TIME COMMAND
 7158 jm        16   0  964 34300  31m 2280    0  1.8  3.1   0:02 perl
 7409 jm        17   0  964 34300  31m 2280    0  0.0  3.1   0:00 perl

Looking at the above 'top' output, it appears that the two spamd processes listed are sharing a pitiful 2280KB of memory pages – 3.4% of their total memory usage. However, all's not as it seems.

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