Tracking Campaign ID (CID) , Lead Channel source Tracking & Attribution

Hi all,

We are encountering an issue with tracking campaign IDs in Adobe Marketo. We use a hidden form field named "CID_latest" in our forms to capture the campaign ID value from a cookie and pass it to Marketo via REST API along with other fields.

In Marketo, we have two custom fields in the lead record:

CID - Intended to capture the initial campaign ID for first touch attribution.
CID_latest - Intended to capture the most recent campaign ID for last touch attribution.
Scenario and Problem:

When a user lands on our site with the URL www.mysite.com/?cid=test_email_marketo_test_test, both the CID and CID_latest fields should ideally store "test_email_marketo_test_test". However, the CID field does not capture this value, while CID_latest does.
When a user lands with the URL www.mysite.com/?cid=test_paid-search_marketo_test_test, CID should retain the first campaign ID "test_email_marketo_test_test", and CID_latest should update to "test_paid-search_marketo_test_test". Currently, CID does not retain the initial value.
This discrepancy is affecting our ability to accurately track first touch and last touch attributions.

Could you please assist us in resolving this issue so that both custom fields capture and retain the correct values as intended?