Looking on the internet deeply has found these results:

many many happy returns of the day is the most popular phrase on the web.

many more happy returns of the day 1271,000 results on the web	many many happy returns of the day 12,520,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Now, "Many happy returns of the day." Apart from the happy return of Conservative bottoms to where they rightfully belong? Lies like birthday many happy returns of the day when there won't be any and... Many happy returns of the day, dear! Many happy returns of the day, Steve. That is another happy occasion, and good reason to wish her many happy returns of the day. Music* If that happy day could return Tracing back to that fading memory Music Thank you very much, and many happy returns* to the Commissioner on his name day, as we say in Greece.	And many happy returns to our host. Thank you very much, and many happy returns to the Commissioner on his name day, as we say in Greece. Now, "Many happy returns of the day." Music* If that happy day could return Tracing back to that fading memory Music Lies like birthday many happy returns of the day* when there won't be any and... That is another happy occasion, and good reason to wish her many happy returns of the day. Many happy returns of the day, Steve. Many happy returns of the day, dear!

many more happy returns of the day

1271,000 results on the web

many many happy returns of the day

12,520,000 results on the web

More popular!

Now, "Many happy returns of the day."
Apart from the happy return of Conservative bottoms to where they rightfully belong?
Lies like birthday many happy returns of the day when there won't be any and...
Many happy returns of the day, dear!
Many happy returns of the day, Steve.
That is another happy occasion, and good reason to wish her many happy returns of the day.
Music* If that happy day could return Tracing back to that fading memory *Music
Thank you very much, and many happy returns to the Commissioner on his name day, as we say in Greece.

And many happy returns to our host.
Thank you very much, and many happy returns to the Commissioner on his name day, as we say in Greece.
Now, "Many happy returns of the day."
Music* If that happy day could return Tracing back to that fading memory *Music
Lies like birthday many happy returns of the day when there won't be any and...
That is another happy occasion, and good reason to wish her many happy returns of the day.
Many happy returns of the day, Steve.
Many happy returns of the day, dear!