Lead wires of medical implants can pose a severe safety risk due to RF-induced heating. Risk assessment typically involves determination of the transfer function. This study shows that the transfer function may drastically change if a second wire is located close to the lead wire. An explorative simulation study has been performed investigating the impact of inter-wire spacing and wire length on the alteration of the transfer function by the second wire. Results reveal that in particular insulated wires may show very strong enhancements (>100%) in induced currents if a second wire is present.