Same task getting accepted by 2 users at the same time

Hi Team,

we want to understand the behaviour of user input task being accepted by the users. Scenario is we have group of users to whom the created user input task will be assigned and hence two different logged in user of same group in a site opens the tasks at the same time and once use accepts it then when other user clicks on accepts hes getting the message saying User1 accepted the task with a reassign button. When User2 clicks on reassign the tasks gets moved from User1 as well eventhough it was accepted by User1. Kindly make me understand the purpose and best way to achieve the previlages of user input tasks.

Regards,

Sameer