1) You can duplicate the field and give it a new alias, so this means you're using a different copy of the field in each worksheet where you want a different alias name:
2) Yes you can create a calculated field using an if or case statement. E.g:
if [market] = 'APAC' then sales end
or set a parameter so that the calculated field will be updated by that:
if [market] = [market parameter] then sales end
Thanks for the detailed information.
One doubt which I have in mind, while duplicating the original field multiple times in order to create aliases, Tableau will create new field and will allocate the memory spaces multiple times, the number of times we are duplicating the variable. So it will be a lot of wastage of memory in order to just create an alias. Please correct me if I am wrong.
How many times would you need to duplicate it/how many worksheets would you need to do this for?