i`m setting up a "comm" line from pin 13 of one arduino to the pin 13 of another.
That should be no problem.
getting 1 volt readings when the pin is "HIGH"....booooo
That is not being caused by the internal LED you have something else wrong. Grounds not joined or pin mode not correct (one has to be an input and the other an output).
The location of the resistor depends what board you have but you should be able to trace it back from the LED.
my 10k to ground, and the two leds are munching a considerable amount of that MEGA power!!
No do the sums.
1K resistor (assume no LED) = 5mA
10K resistor = 0.5mA
So for two connected together you have 5 + 5 + 0.5 = 10.5mA.
An arduino pin can comfortably supply twice that. And four times that at an absolute maximum.