Intracellular delivery of biomacromolecules is a challenging research field in chemical biology and drug delivery. We previously reported a peptide named L17E, which successfully delivered functional proteins, including antibodies, into cells. However, relatively high concentrations of L17E and proteins are needed. In this study, we prepared dimers of L17E and its analog L17E/Q21E. Dimerization of L17E increased cytotoxicity leading to reduced intracellular delivery compared with L17E. On the other hand, the dimers of the L17E analog, L17E/Q21E, especially when tethered at the N-termini, yielded a comparable level of intracellular delivery with L17E at decreased amounts of delivery peptides and cargoes.