I found out the problem!, hibernate needs one of the duplicated columns to be mapped with insert="false", update="false"
To do that on grails you have to add that to the mapping, like this:
static mapping = {
datasource 'xxxxx'
table 'clients'
version false
id column: 'third_party_rowid'
thirdParthy column: 'third_party_rowid', insertable: false, updateable: false
....
}