How can i replicate many database into one, by avoid primary key collision?

I have n number of databases and I have to collect data from those into one database. The databases has some specific value (e.g. currencies) which I want to update from the collector database(of course I want this to update for all databases). So in the first case I need to avoid primary key collision because i don't want to loose data. I think that setting up auto_increment.increment and auto_increment.offset, can do the trick, but in the second case i have to identify specific rows in all databases. What kind of technology and topology can I use?