How do I identify fake or duplicate seed before I sow it?

You cannot judge seed purity by eye alone, but several checks catch most fakes. First, buy only sealed company bags, never loose seed claimed to be a famous variety. Check the certification or truthful label tag is properly stitched (not pasted on later), and that the lot number on the tag matches the bag and the bill. Look at the test or validity date, the germination percentage printed, and that the seal is not tampered or re-stitched. Avoid bags with spelling mistakes in the brand, blurry printing or a price that is suspiciously low. Keep the bill, the empty bag and the tag until the crop is up, because these are your only proof if germination fails. The real test is a home germination test before sowing (count how many seeds out of 100 sprout). If something feels wrong, show the bag to your KVK or the seed inspector at the agriculture department before sowing. Confirm doubtful tags with the seed dealer or KVK.