TYPO3 Core

I cannot reproduce the problem. For testing I've used this setup:

enctype = multipart/form-data
method = post
prefix = tx_form
confirmation = 1

postProcessor {
    1 = mail
    1 {
        recipientEmail = your@email.com
        senderEmail = your@email.com
    }
}

10 = RADIOGROUP
10 {
    class = fieldset-subgroup
    legend {
        value = Radio group 1 (with values)
    }
    name = radiogroup1

    10 = RADIO
    10 {
        label {
            value = Option 1
        }
    }

    20 = RADIO
    20 {
        label {
            value = Option 2
        }
    }

    30 = RADIO
    30 {
        label {
            value = Option 3
        }
    }
}

20 = RADIOGROUP
20 {
    class = fieldset-subgroup
    legend {
        value = Radio group 1 (without values)
    }
    name = radiogroup2

    10 = RADIO
    10 {
        label {
            value = Option 1
        }
        value = option4
    }

    20 = RADIO
    20 {
        label {
            value = Option 2
        }
        value = option5
    }

    30 = RADIO
    30 {
        label {
            value = Option 3
        }
        value = option6
    }
}

100 = SUBMIT
100 {
    name = submit
    value = Submit
}

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