Google's John Mueller responded with SEO advice on how a company can use two different TLDs for its company. The company wants to use the .co.uk for normal search and web traffic but .digital as a TLD for some of its marketing campaigns.
John Mueller provided the following advice for this on Reddit. He said:
(1) Do a normal site migration first (301 all pages, etc) from .digital to .co.uk
(2) Use the new domain (i.e. .co.uk) to build up your web presence.
(3) Make it so that it's super-obvious to search engines which domain you want.
(4) Having your email address with the other domain is unproblematic - that's not used for SEO, he wrote.
(5) When things are settled down, if you still want to basically run two sites (even if they're the same), doing something like the canonical is fine. I just wouldn't do that during the time you're trying to get established for search engines, and especially not if you want to actually move domains.
He added that, "301 redirects are a strong signal for canonicalization, rel=canonical is less so."
In essence, your website that search engines access should really only show one site, one TLD, and the other TLD should be virtually invisible to search engines.
Forum discussion at Reddit.
