What's the effect of using int data type to preload the buffer and using unsigned char to fetch the data? Well, that could vary, but it wouldn't repeat the 2nd, 4th, 6th, and 8th characters, would it?
yes it would, look here
assuming stuck low
storing 'a', 'b', 'c' as ints
first zero, then a goes into 0
first zero, then b goes into 2
first zero, then c goes into 4
reading back
reading high (0) then low (1) will read 0 which is 'a'

Thus the point the OPs 'test' is missing (looking at LSB only) is that the read int 0 will read 'aa'

storing 'a', 'b', 'c' as ints
a goes int0 0
b goes int0 0 (1 with lab adderss stuck low)
c goes into 2
reading back
reading 0 or 1 will read 0 which is 'a'
...

anyhow, your point "do not debig hardware with C code" is extremely valid.

Erik