In our case we use the SFDC database as the leading database. When a known customer fills in a Form in Marketo it can be happen that something will be overwritten in SFDC. Par example: In SFDC First name Jan will be overwritten with Jane by filling in a Form on a Landing Page! This can make your SFDC database corrupt. Even when in SFDC more then one Contacts by a Company have the same such called "info@" email address can create a lot of errors.
Solution can be to setup some Shadow Fields in Marketo witch can be used in Forms:
And then follow/setup the following flow in Marketo:
We are now working on this. As soon as implemented I will show the results.
Pieter van Dijken