I wonder if that prototype may have been the original working design, and such prototype may have been designed around 1985 or maybe even 1984? Makes me wonder if there were 1980s prototypes for the other denominations around the same time period?
And I agree, the official version with the birds theme was much better. Though the serial number format on the prototype implies that the Bank of Canada may have been originally intending to incorporate the all-numeric format from the 1979 $5s and $20s on all the other denominations, but ultimately decided to continue the alpha-numeric prefixes instead.
It turns out the Bank of Canada made the right call in the end, though the serial number font on the prototype was very unique and nothing like the version seen on the 1979 banknotes nor the font currently in use since 2001. Had they kept the all-numeric format, my interest in serial numbers would not have been prevalent anymore.