While the verb is Desket ... it will then be desketerler not as written desketlerler !
desket is not a verb. destek means support as a noun. The verb to support is destekle*mek*
Why would the ler come twice at the end? Can anyone explain?
Because it is conjugated for the third person plural(they support= onlar desteklerler)
destekle+ r+ ler