Deleting test orders from development site.

[BillTuttle]

I'm working on importing orders from our old system into our Shopify account (using the Matrixify app), mostly so that it knows what our best sellers are for sorting and recommendation purposes. I loaded a test batch with a few orders, found some things I needed to fix, and was trying to delete them so I could start over. I figured out that the orders had to be archived first before the delete command would show up. However, when I click the delete button, I get this message (emphasis mine):

This can't be undone. Order ###### will no longer be available in your admin, but a record will be kept in Shopify's database for tax purposes.

Exactly what 'tax purposes' is this referring to? Just to be clear, these are (copies of) real orders, but they were already completely handled before we started to move to Shopify, and I'd like to be sure we don't get double taxed for these somehow.

Also, is there something I should have done differently to let Shopify know that this was test data?

(I understand that Matrixify is a third-party app, and I'm not looking for instructions on using it. I'm just trying to make sure I can get the data on the Shopify end straightened out.)