Based on this product's specifications, here are some alternatives and similar models
Adjustable Double Leash Splitter Chaba model 657914, 1.6/42–74 cm, burgundy
Summary description:
Chaba adjustable double leash splitter (model 657914) is a burgundy accessory that converts one lead into two with an adjustable length of 42–74 cm and a 1.6 cm width specification. Designed for walking two dogs from a single handle, it features split connection points for secure attachment and length adjustment to reduce tangling and improve control during walks.