Is there a lightning cable power splitter / double charger?
No, this is not possible to make.

Your question implies that you think of the Lightning cable as solely providing power in the form of two wires with +/- electricity. This is not the case.

In addition to simply power supply, the cable also contains wires that are used for communication between the charger and the device. When you plug your phone or other device into the charger, they start negotiating right away what kind of supply is needed. The charger acts differently according to the needs of the device plugged in.

This is the reason why you cannot have both a phone and AirPods (for example) spliced into the same charger cable - as the negotiation process would go hay-wire with multiple devices communicating on a protocol that is designed strictly for one-to-one communication.

I would recommend instead getting a charger with multiple USB outputs. These can be bought quite cheaply - for example IKEA has a cheap charger with 3 USB outputs for plugging in Lightning cables. 

In order to keep the Lightning cables short, you would have to extend the use of the 110/230V cable and place the actual charger nearer your devices.