Connect multiple devices to one power cord
Yes, you are correct!

You are making a parallel circuit, so:

$$V_\text{total} = V_1 = V_2 = V_n$$

$$I_\text{total}=I_1+I_2+I_n$$

The current you have to sum, so if one camera needs 2A, the total current will be:

Number of Cameras times 2A.

The voltage is the same for every camera, so you need ensure 7.4V.

You need to do something like this:



Where V its you power supply and each R are your cameras.