I saw this link that addresses and 'solves' collision problems. http://k9jm.com/CIV_Router/CI-V%20Router.htm
I think you can have multiple devices per port, minimizing collisions based on port sharing selection.

I also read this: http://k9jm.com/CIV_Router/CIV_Electrical_Interface.pdf , but I think the author misunderstood the MAX232 interface spec sheets. The author states: "Here they do what appears to be the insanity of shorting pin 11 to pin 12 to the CI-V bus, which are in input and the output of the level translator. Looking at the datasheet for the MAX232, this part has Vih=2 and Vil = .8 volts. Combining this with that of the radio, Vil = .8 volts and Vih = 3.6v The Max232 also has an output source current of 1ma, and an output sink current of 3.5 ma. Because the input is connected to the output, the CT17 can only sink a maximum of 2.5ma, which is far less than the current sinking capabilities of the radio."

I looked at the spec sheet, and from what I see, the Rout has a diode on the output, with a pull up resistance of 1.3K, and an output resistance of 300 ohms. This is consistent with the parameters on the spec sheet. This is what I see - the diode with the pull-up resistor which essentially gives it open collector/drain characteristics. This will allow shorting of pins 11 and 12 on the CV-17 interface. If you put a dead short on Rout of the device, the source 5 VDC divided by the 1.3K pull-up plus the load resistance of 300 ohms, becomes 5/1600 = 3.125 mA, rounded up to 3.2mA, as specified in the spec sheet. Any number of CV-17 drivers is not going to beat a dead short, its not going to change anything.

What is important is the issue of collisions between two (or more) talkers.