cron running tasks twice simultaneously!

I bought a new drive and set up a RAID on my G4 running OS 10.3.9. I have noticed that when the periodic daily task runs at night, it apparently is called twice and tries to run both processes simultaneously, which causes all kinds of problems since while one daily task is trying to move and compress files, the other task is already doing it and has a lock on the files, etc.

So I looked to see what crontabs were loaded:
Gandalf:~ root# ls -l /var/cron/tabs/
total 8
-rw------- 1 root wheel 1093 16 May 09:06 root

I then tried to make sure the default in /etc/crontab wasn't running in addition to this one by disabling it:
Gandalf:~ root# ls -l /etc/crontab
---------- 1 root wheel 296 2 May 11:22 /etc/crontab

This did not keep the problem from coming back, as last night my daily log shows everything repeated twice. This is the content of the lone crontab found in the /var/cron/tabs/ directory:
Gandalf:~ root# cd /var/cron/tabs/
Gandalf:/var/cron/tabs root# more root
# DO NOT EDIT THIS FILE - edit the master and reinstall.
# (/Users/derekhed/bin/rootcrontab installed on Mon May 16 09:06:18 2005)
# (Cron version -- $FreeBSD: src/usr.sbin/cron/crontab/crontab.c,v 1.17 2001/06/16 03:16:52 peter Exp $)
# /etc/crontab
SHELL=/bin/sh
PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin
HOME=/var/log
#
#minute hour mday month wday who command
#
#*/5 * * * * /usr/libexec/atrun
#
# Run daily/weekly/monthly jobs.
15 3 * * * periodic daily
30 4 * * 6 periodic weekly
30 5 1 * * periodic monthly

3 0 * * * /Users/derekhed/bin/httpd.logrotate > /dev/null 2>&1
9 0 * * * /usr/local/bin/webalizer -Q
57 23 * * 6 /Users/derekhed/bin/BU_MySQL.sh -p *censored!* /Volumes/Ren/backups/db/entire_db.sql
27 * * * * /Users/derekhed/bin/FetchCache 0 > /Library/StartupItems/SETIatHome/bin/cache/Fetch0.out 2>&1
47 * * * * /Users/derekhed/bin/FetchCache 1 > /Library/StartupItems/SETIatHome/bin/cache/Fetch1.out 2>&1
36 1 * * * /Users/derekhed/bin/create_dmg.sh
*/5 * * * * /Users/derekhed/bin/prog > /Library/WebServer/Documents/prog.out
Note that there is only ONE call to periodic daily here. Why would it try and run it twice? Can anyone think of where I should look next? Any feedback is appreciated, thanks!