Solved, i have to download the last version of SthttpRequest, in last version i've found a new method for multiple uploads:
[request addDataToUpload:imgDataThumb parameterName:@"thumb" mimeType:@"image/jpeg" fileName:@"thumbname"]; [request addDataToUpload:imgDataBig parameterName:@"image" mimeType:@"image/jpeg" fileName:@"imagename"];