RE: Are contacts receiving our emails twice or more?
Hi,
The option "Bypass email deduplication" is for the case that more than one contact record in the target segment has the same email address, which is different from "two or more Segments that might contain duplicate Contacts".
Suppose now there are two segments containing the same contact with this option set as Yes.
If they are in the same swimlane.

The email has been delivered to the contact only once.

And if they are in different swimlanes.

Although there will be two sent records, only one of them will be delivered.
Here are the descriptions of "Email sent" and "Email delivered".

So you do not need to worry about the duplicate delivery to the same contact in different segments.