duplicate entries in s3 bucket listing

I wrote a simple program that just writes all keys in a bucket to a file.
the golang-goamz output starts with:

.com/451/45158_146.png
.com/451/45158_146.png
.com/451/45160_1261.png
.com/451/45160_1261.png
.com/451/45162_1261.png
.com/451/45162_1261.png
.com/451/45164_1261.jpg
.com/451/45164_1261.jpg
.com/451/45166_576.jpg
.com/451/45166_576.jpg

as you can see, pretty much all duplicates.

a similar script in python using the boto library to get a list:
.com/451/45157_146.png
.com/451/45158_146.png
.com/451/45159_1261.png
.com/451/45160_1261.png
.com/451/45161_1261.png
.com/451/45162_1261.png
.com/451/45163_1261.png
.com/451/45164_1261.jpg
.com/451/45165_1261.jpg
.com/451/45166_576.jpg

no duplicates here, this is also in line with the s3 web dashboard.

my code is basically just (edited for brevity):

func main() {
    auth := aws.Auth{access_key, secret_key}
    s3 := s3.New(auth, aws.USEast)
    bucket := s3.Bucket(my_bucket)
    get_aws := GetFilesAws(bucket)
    for in_aws := range get_aws {
        fmt.Println(in_aws.Key)
    }
}

func GetFilesAws(bucket *s3.Bucket) (in_aws chan *s3.Key) {
    in_aws = make(chan *s3.Key)
    go func() {
        marker := ""
        for {
            listresp, err := bucket.List("", "", marker, 1000)
            if err != nil {
                panic(err)
            }
            if len(listresp.Contents) == 0 {
                close(in_aws)
            }
            for _, key := range listresp.Contents {
                marker = key.Key
                in_aws <- &key
            }
        }
    }()
    return in_aws
}

maybe my code is wrong but I believe i implemented correctly according to the spec @ http://godoc.org/launchpad.net/goamz/s3#Bucket.List