通过PHP使用具有相同名称的多个关键字段的AX Web服务

I'm trying to consume a webservice in AX 2009 through PHP, have done that before without any problem, this time I need to produce an XML with multiple keys with the same name, for the update part I found a working solution, but I need to select the record before I update it and there it fails.I'm trying to consume a webservice in AX 2009 t