I dont think there is any palin at all that support multiple encoding.
Notepad ++ cannot display multiple encoded data in the same file.
But it is very much possible that you can use different language in the same text file. But it must have to be same encoding.
日本 this is in japanese
বাংলাদেশ this is bengali.
한국 (i think this is korean)
But all used same encoding (UTF-8 in this case)
And Of course the browser you are using cannot display two encoding same time.
if you have development idea. You can try simple test on encoding issue. try to print two different encoded data in the same page. you will get garbage output.
But if you might get some pretty interesting issue where it will seems that you are getting data in different encoding... as example
say you have two different text file with two different encoding.
both containing Japanese text. If you copy some text from one text file and paste it to other you will see a successful pasting. you must ask that they are different encoding how come they are getting pasted in the same text file?
the answer is when you copy some text it get copied in UNICODE and also pasted as unicode(with my little programming knowledge all text that is displayed on windows are in unicode. If you dont convert text to Unicode you cannot print them properly). But when user save the file, it get saved in its proper encoding....................