Rules Analysis
WFDF 2017 Rules
17. Fouls
.

Any reference in section 17 to 'contact' is considered to be a reference to non-incidental contact, as, per 15.1, a foul is specifically defined as "non-incidental contact".

17.4.
4
.

Defensive Throwing (Marking) Fouls:

17.4.1.
1
.

A Defensive Throwing Foul occurs when:

This rule was changed from the previous rulebook version
This rule was added from the previous rulebook version
This rule has updates in the next rulebook version
17.4.1.1.

A defensive player is illegally positioned (Section 18.1), and there is contact with the thrower; or

17.4.1.1.
Children
17.4.1.1.
Associates
WFDF 2021-24 Rules
17.6.1.1.

A defensive player is illegally positioned (Section 18.1), and there is non-minor contact between the illegally positioned defensive player and the thrower; or

If a defender is legally marking the thrower and then a second defender commits a double team, the second defender is deemed to be the illegally positioned defensive player. Therefore it would only be non-minor contact between the thrower and the second defender that would automatically result in a defensive throwing foul.