Why are there phpbb entires in my mybb database

[azalea4va]

I installed mybb from scratch.  To the best of my knowledge, it was just a generic install.   I have never used or installed phpbb.

When I create database backups from within mybb, the backups just have tables whose names start with mybb.  But when I look directly (the webhosting service where the MyBB resides uses phpMyAdmin - 2.8.0.1) in the data base, it contains a bunch of tables with names starting with "mybb_" and a bunch of tables with names starting with "phpbb_". Attached is a complete list of the tables. The table phpbb_users has entries with the following valies in the username field.

Anonymous                                                                          ·
egroup_admin
AdsBot [Google]
Alexa [Bot]
Alta Vista [Bot]
Ask Jeeves [Bot]
Baidu [Spider]
Bing [Bot]
Exabot [Bot]
FAST Enterprise
FAST WebCrawler
Francis [Bot]
Gigabot [Bot]
Google Adsense [Bot]
Google Desktop
Google Feedfetcher
Google [Bot]
Heise IT-Markt [Crawler]
Heritrix [Crawler]
IBM Research [Bot]
ICCrawler - ICjobs
ichiro [Crawler]
Majestic-12 [Bot]
Metager [Bot]
MSN NewsBlogs
MSN [Bot]
MSNbot Media
Nutch [Bot]
Online link [Validator]
psbot [Picsearch]

Can nayone explain where these phpbb_ entries came form, and can they be safely removed?

[.m.]

such tables with phpbb prefix can be safely removed. can't say how they appeared into your database.