Item inventory merging is a feature that allows you to merge inventory from 2 identical items that have different Item ID's.
For example, you have 2 tables in stock with an item ID of 1067. The SKU for this item is PL4260-2L. You want to go ahead and order another identical table so you have multiple on hand since you sell this item often. So you click the options menu for the item and click Order Similar for Inventory. This creates a new item with all the same details, and you get it ordered. The item ID for this item is 1069. Remember they will have different item ID's since an item ID is like an order ID, it is unique for every single order so you can track that order independently from other orders.
Once the item is received, you now would have both item 1067 and 1069 in stock, both identical. 1067 has a qty of 2 and 1069 has a qty of 1. They both have the same SKU since they are both the same model.
OrderTrac does have an item catalog which allows you to track the qty by SKU. The item catalog allows you to add items you like to keep in stock to the catalog so you can easily see you have a qty of 3 in stock for SKU PL4260-2L.
However, in some situations (especially if you using item merging in OrderTrac classic), you may want to merge the two items together so you only see one item ID in stock with a qty of 3 rather than 2 item ID's with a qty of 1 & 2.
The major downside of using this feature is you lose a little bit of history for these items. Let's say the cost for item 1067 was 500.00. The cost went up by the time you order item 1069, so the cost for this item is 600.00. By leaving the items separate, you can keep the history of the items in tact. This means you can look at your items and easily tell: I ordered 1 item in January with a cost of 500, then I ordered 1 more in March with a cost of 600. This is why using the item catalog feature is preferred and a good reason to use SKU's as your method of tracking total qty available by each unique product.
However, if these downsides are not a concern for you, you may prefer to enable item merging to clean up your inventory list. Many stores will tag their inventory with the item ID, so by merging the two item IDs together, it makes it easier for sales associates to look up items by item ID and see the true qty in stock.
Item inventory merging is not enabled by default. To enable item inventory merging, check the Allow Item Inventory Merging checkbox found in Settings > Account Settings.
When you receive an item either from the Receiving page (Items > Receiving) or just by manually updating an item's status from On Order to Received, OrderTrac will check your inventory to see if you have any older items that match the item you just received.
It will first check for items with the same SKU and Description exist with an item ID < the item you received. If no items found, it will check for items with the same Description, and if that isn't found then items with the same SKU. It will always only search for items with an Item ID less than the item you received.
If a match is found, a dialog will display with an alert that an eligible matching item was found, and you can choose to merge the inventory if the item you just received with the existing item that was found.

If you want to merge the two together, select the item from the list and click Select. There may be multiple matching items so in that case, you probably want to select the oldest item (smallest item ID). Once you click Select, the quantity will be moved from the newer item to the older item. So in this case, item 1067 will be updated to have a qty of 3, and 1069 will be updated to have a qty of 0. Since 1069 has a qty of 0, the status will be updated to Closed to clear it out of view.
You can also initiate a merge manually from the items page. Just click the options menu for the item you want to merge into an older item, and select Merge item inventory.

This will make the same dialog appear where you can select an item to merge:

If there are no eligible items found, you will simple see a message that says no eligible items found.
Customer items are not merged. You do not want the Item ID changing for customer items since the item ID is printed on the sales order and otherwise would just be hard to track. In some cases, it is possible for and item to both be sold and in inventory.
Let's say you have an item with a qty of 6 originally. 2 have been added to a sales order, while the other 4 are still in stock. If you were to merge that item into an older item, only the 4 in stock will merge with the older item. In this case, the original item will remain with a qty of 2, so that item continues to show properly on the sales order.
