@iranig
The first thing to check is probably obvious and you already did it, but make sure that you have the number of copies set to 1 in the plugin settings. Since you said it is two or three, and not the same every time, I guess that it is not a simple setting issue.
The next step is to check your print trigger. By default, this is set to use the “ThankYou” action hook, that is issues by WooCommerce. This works with every site but it has many problems and so isn’t recommended. It is not intended for this purpose and can sometimes cause jobs to be missed, to re-print, print late and a few other issues. If your site is configured to use the “ThankYou” hook, as a print trigger, then please change it to one of the other options, as appropriate for your site (usually, when an order is assigned the “processing” status is best for most sites).
If you already have changed the trigger, then a possible cause is that another plugin on your site is changing the status of orders sometimes. If your trigger is when the processing status, and a plugin changes the status, and then changes it back to “processing” then it would trigger another print. I haven’t yet seen a plugin that does this, but it is entirely possible.
Finally, it is possible that network reliability issues can cause multiple printer. Our printer makes two connections to your site when printing, one to retrieve the print job, and another to confirm that it has printed. If the second connection doesn’t succeed, then the printer will end up getting the same job again next time. This can be surprisingly common if you are using a WiFi model printer in a kitchen, where microwaves and many metal surfaces can cause signal problems. But, if this were the case, it would quite rare (unless the network is extremely unreliable), I don’t know how often your experience this issues?
