Help me understand our form conversion metric when broken down by last touch channel. Please explain in details

Hello the amazing Adobe Community,

I am looking to understand a metrics.

• We have form conversion set as Segmented “Visit Container” with event## to fire when user submit a form
• Then create a calculate metrics using that Visit Container Segment + the (Visit) metric is our Form Conversion

We want to understand why when we have last touch channel broken down and when we sum the form conversion for each of the channel it doesn’t add up to the “Deduplicate total within the workspace” example using dummy numbers. Can someone explain what is causing this? We understand that visits and sum should have slight difference of approx. 5% but for our form conversion calculated metrics its >15% difference between workspace number and total number. Explain in technical term is also welcome. I want to understand Adobe logic.