Hi Vishal,
Is restricting of multiple simultaneous login a specific requirement? what is the version of your BO? please provide some more details as to whats driving you for this requirement.
Please refer to below note and see if you are facing any issue as below.
1764372 - Multiple sessions created for a single User when Web Intelligence reports are based on .unx Universe, BICS or DSL in BI 4.0
Thanks
Mallik