When you find there are Double Entries in Biz Analyst Application.
As you can see here, voucher no. 689 is showing twice with amount 48,257.
But in Tally there is only one entry with voucher no. 689 with amount 48,257.
So do not open backup or restore any data in Tally while syncing the data and even see to it there should not be other companies with same name or else just turn Off Biz Analyst Desktop App while opening backup.
In this case data gets OVERWRITE and Show Double Entries OR Incorrect Amount in Biz Analyst Mobile application.
Open Biz Desktop App> Select Company> Edit> Additional Settings> Re sync Data.