Error when uploading product content on iTunes connect

I am working on project which download content from iTunes connect when user purchase. but I can't upload product content on iTunes with application loader. I am getting following error during upload

ERROR: ERROR ITMS-4000: "The package can't include two files with the same name 'mzl.kzekbupn.png' but with different size or checksum." at Software/SoftwareMetadata/SoftwareInAppPurchase

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