The double  sequence does not occur in native English words, but is found in some words derived from foreign languages such as Aaron and aardvark.
ðə dˈʌbəl sˈiːkwəns dʌznˌɑːt əkˈɜːɹ ɪn nˈeɪɾɪv ˈɪŋɡlɪʃ wˈɜːdz, bˌʌt ɪz fˈaʊnd ɪn sˌʌm wˈɜːdz dᵻɹˈaɪvd fɹʌm fˈɔːɹən lˈæŋɡwɪdʒᵻz sˈʌtʃ ɐz ˈɛɹən ænd ˈɑːɹdvɑːɹk.