Lightspeed and Shopify integration split order for products purchased in store

[JimmyFlashSew]

So we have 2 brick and mortar stores that use Lightspeed as the Inventory system and for POS.

When a person buys all the products in store, Shopify tends to split the fulfillment between the 2 stores.  How and why does Shopify do that? and will that affect my inventory count in those 2 locations?