PHP array_merge add to XML

Hi, I need to add ' det ' with attributes => det_nItem to XML file, but it brings the last value twice. in the current script it brings me the following result: <?xml version="1.0" encoding="UTF-8"?> <NFe xmlns="[login to view URL]"> <infNfe versao="4.00" Id="NFe"> <det nItem="3"> <prod> <cProd>IN020007</cProd> <cEAN>SEM GTIN</cEAN> </prod> <det nItem="1"> <prod> <cProd>IN020005</cProd> <cEAN>SEM GTIN</cEAN> </prod> </det> <det nItem="2"> <prod> <cProd>IN020006</cProd> <cEAN>SEM GTIN</cEAN> </prod> </det> <det nItem="3"> <prod> <cProd>IN020007</cProd> <cEAN>SEM GTIN</cEAN> </prod> </det> </det> </infNfe> </NFe> But I need like this: <?xml version="1.0" encoding="UTF-8"?> <NFe xmlns="[login to view URL]"> <infNfe versao="4.00" Id="NFe"> <det nItem="1"> <prod> <cProd>IN020005</cProd> <cEAN>SEM GTIN</cEAN> </prod> </det> <det nItem="2"> <prod> <cProd>IN020006</cProd> <cEAN>SEM GTIN</cEAN> </prod> </det> <det nItem="3"> <prod> <cProd>IN020007</cProd> <cEAN>SEM GTIN</cEAN> </prod> </det> </infNfe> </NFe>