Hello
There is one configuration for this. Activate the debug mode.
Go to Sales/Inventory Configuration, search and active the "Units of Measure" feature and go to user and give the access of "Manage Multiple Units of Measure".Now go to menu Sales -> Configuration -> Units of Measures Cateories.
select any category and open form view of that category. Into that there is one option "Group Products in POS". now the products and products UOM which categories Group Products in POS is checked. that products showing in group in pos.
for eg. UOM category weight and into this i have checked the Group Products in pos is checked.
now the UOM kg have the UOM category weight.
product Orange have the UOM kg. so this product is showing combine into the pos.
IF you need combine then mark as checked the option "group products in pos". if you need seperate then
mark as uncheked the option "group products in pos" from UOM categories.
I hope this will helps you.