In short, I tried to use something like:
redirect 301 /page1/ https://www.newsite.com/page3/
redirect 301 /page1/page2 https://www.newsite.com/page4/
The first redirection worked fine while the second redirected me to: newsite.com/page3page4
Solution - I had to switch to use REGEX to limit the redirection to only one specific page and not everything that begins with that address.