It may mean that the ratio of the output power of an electric or optical circuit to the input power should be doubled.
ɪt mˈeɪ mˈiːn ðætðə ɹˈeɪʃɪˌoʊ ʌvðɪ ˈaʊtpʊt pˈaʊɚɹ əvən ᵻlˈɛktɹɪk ɔːɹ ˈɑːptɪkəl sˈɜːkɪt tə ðɪ ˈɪnpʊt pˈaʊɚ ʃˌʊd biː dˈʌbəld.