What happens when anarchists fundamentally disagree?

Question

agreement=society=order
anarchy=idealism=chaos
chaos=no agreement=no society=no order

Answer 1

no order=hidden agenda
hidden agenda=follow the money
follow the money=enemies of democracy

Answer 2

I doubt anyone here agrees with your premises. Nevertheless, depending on the circumstances, anarchists express disagreement or dissent by:
-separation by time ("taking turns")
-separation by space ("voting with the feet")
-decision by game of luck
-withdrawing participation
-withholding support
-ad hoc discussion
-formal debate
-arbitration by mutually-agreed upon third-parties
-arbitration by community assembly
-arbitration by ad hoc peer council
-immediate recall of delegated roles or tasks
-disruption/heckling
-ridicule/mockery
-attacking reputation
-disruption/obstruction
-shunning
-consensual duels
-feuding & pranks
-banishment
-property destruction
-combat

Answer 3

Fundamentally most anarchist agree otherwise they would be or are something other than anarchist.

With anarchy you are allowed to disagree on all other matters which equals freedom.  Here you do not have to agreement or have to submit to those things you do not agree with.  

Those who would disagree with anarchy are those who believe others should not be able to disagree and act separate from the rule of others.  Without anarchy you wish to be controlled or to control what other should think, act, or do.