1. In your Highrise connector [sync options] set "External connector
tag" to something like "Highrise",
any Highrise contact touched or created by Yoxel in Gmail/Exchange
will be tagged with this so you'll see what came from Highrise.
2. You may not want to enable the sync for all your Gmail/Exchange
contacts so in the [sync options] of your Gmail/Exchange connector
switch to the "Only for tagged imported contacts" mode and specify the
list of tags. It's a good idea to have at list one tag there that is
matching your Highrise connector's external tag, "Highrise".
Any questions?