Note that your Vicidial version is 2.2.1 (version 2.0 is "goautodial" which is just an "installer" for Vicidial, not actual software ...).
When an agent enters the "meetme room" (
http://www.voip-info.org/wiki/view/Asterisk+cmd+MeetMe) as generated by Vicidial, there are specific settings applied to cause those sounds. The underlying vicidial scripts CAN be altered to avoid those sounds (in theory ...), but I do not believe this can be done within the Vicidial settings. I believe it must be done in the extensions.conf file directly. Be careful in there, it's easy to break Vicidial while you're in. There is a "fresh" copy of the file in the /usr/src/astguiclient/trunk/ folder (although I'm not positive that's where it is in Goautodial ... actually it may not be at all .. you may have to "locate extensions.conf" to find the fresh copy!).
Consider upgrading, you have a very old version.
Also consider using "Vicibox.com" which has a more recent installation and will install the Latest version of the software (with a lot more features!). Also consider installing a spare copy on a virtual server for testing (then you don't have to worrry about breaking it!)
Happy Hunting!