Hi @nekinekic ,
I did a test for you.
1\ This is my collection1.
ClearCollect(Collection1,{Name:"Bob"},{Name:"Tom"})

2\ This is my collection2.
ClearCollect(Collection2,{TaskNumber:1,Name:"Bob"},{TaskNumber:2,Name:"Bob"},{TaskNumber:1,Name:"Harry"},{TaskNumber:2,Name:"Harry"})

3\ This is my Table
ClearCollect(Table,{Task:6,Name:"Test",OtherColumn1:"Test"})

4\ Add a button control and set its onselect property to:
ForAll(Collection2 As A,If(CountRows(Filter(Collection1,Collection1[@Name]=A.Name))=0,Patch(Table,Defaults(Table),{Task:A.TaskNumber,Name:A.Name})))
5\ The result is as follows:

Best Regards,
Wearsky
If my post helps, then please consider Accept it as the solution to help others. Thanks.