The Tweakwise app imports products from Magento via the feed. Often, multiple store views are used in Magento to use webshops in other countries/languages. The export extension was built in such a way, that all products can be exported for each individual store view. This means that when a product is sold in two store views, then it will be put in the feed twice. All products need to have a unique number in the Tweakwise app.

So to give every product a unique number in Tweakwise, each product number is compiled as follows:

Magento supplies a product number;
MagentoID  = [66636]  

There are multiple store views in Magento. There's a version of the product for each store in the Tweakwise app;
StoreID = [10001]

The feed supplies us with a combination
TweakwiseID = [10001] + [66636] = [1000166636]

The last number is used by Tweakwise as the official product number. EAN or SKU are often added as a property to enable visitors to search for those codes.