Some companies keep a Master (template) Database and synchronize to this when creating new databases for each project, month, quarter, etc. - however they've chosen to organize their databases. This can save a great deal of time when setting up new databases and ensures every database contains the same settings and Master information.
For Contacts, let's say you enter "Michael Smith Company" as a Contact in your Source database and synchronize it with a Destination database. A Contact "Michael Smith Company" is created, as expected, in the Destination. Now, let's say you edit that Contact in your Source database, maybe the company's name changed to "MSmith Co.". When you synchronize your Source into your Destination database again, Quick Bid does not update the existing "Michael Smith Company" record, it creates a new Contact named "MSmith Co" and leaves the existing Contact untouched. This is done to preserve historical data/states of existing bids. If you want you users to have a fresh set of Contact, based off your Source, they should create new databases and then synchronize those to your Source database.