Hi Kiran,

You can write a client script - onLoad (not Catalog Client Script) on the task form. 

btw, how do you recognize Task 1 and Task 2 ?

You can write a specific script which will check as which is Task1 and show that variable else it keeps it hidden. your variable will only be visible on TASK1 and none of the other tasks created.

Best Regards,

Rahul

Please mark Correct/helpful if it solved your query.