There were some differences even in the mid 90s between AT&T-style awk which was then considered the original/definitive/most-backward-compatible and gawk which

There were some differences even in the mid 90s between AT&T-style awk which was then considered the original/definitive/most-backward-compatible and gawk which was new/shiny (although not /that/ new). I believe both were available in Linux back then. I believe in the above anecdote both were consulted with the emphasis on AT&T-style awk for obvious reasons.