First:
No need to cat the file to awk
correct awk '{print }1' file
This will print every line two times.
awk has this format test {action}
this can be repeated test {action} test {action} test {action}
It this example awk '{print }1' it starts with an action{print } . Since there are no test , it will be true and line will be printed
Next there is an 1test without action . The default action is print so this will also print the line.
{print} gives same result as 1
So awk '{print }1' could be written awk '{print;print }' or awk '{print }{print}'