A comment from one of the blogs I frequent:
Have you ever felt like there was an actual TV land? I watched 'How I Met Your Mother' at 8:30 and 'Heroes' at 9:00, and the actress who played Ted's mom on HIMYM is the same who played Peter's mom on 'Heroes'. I think she was even wearing the same outfit.
But there is a difference in tone between "Your father and I have been divorced...[for] nine months" and "Your father committed suicide".
Posted on Oct 3rd 2006 by Chris W
He's referring to Christine Rose (sometimes credited as "Cristine Rose"), whom I first saw in 'Picket Fences' as Lydia Brock, Sheriff Jimmy Brock's first wife.
But Chris W brings up an interesting point about the internal "life" of Toobworld. Both of those shows take place in New York City, and so far there's no reason to think that they take place in alternate TV dimensions. Wasn't there ever a chance that both characters might run into each other? Or at the very least, one of them would have been mistaken for the other by somebody who knew them.
I don't think there's any hard rule on this. When an actor plays more than one character, there may be something about each of them that is invisible to the eye of the viewer at home in the Real World, but which differentiates them from the other characters played by that actor. This must especially be true in shows where certain guest stars kept re-appearing on the same show, sometimes at least once every TV season.
Vito Scotti on 'Columbo', for example. (Although to give all of those characters he played the proper Toobworld twist, they could all be clones of the mad scientist Dr. Balinkoff from 'Gilligan's Island'.)
Speaking of 'Columbo', in my Toobworld novel I mention how the Lieutenant, as played by Peter Falk, differs from his earlier starring role as Daniel J. O'Brien in ,The Trials Of O'Brien'. You can see it in his eyes, or lack of one.
Falk played O'Brien as though he had two eyes, even if the glass one wasn't always aimed properly. And as such, the character had two eyes.
Columbo may have started out that way, but at some point he did lose an eye. He even refers to this fact in the 25th anniversary episode, "A Trace Of Murder", when he refers to himself and his associate with "Three eyes are better than one."
As for the two maternal roles played by Christine Rose last week, nothing more should be made of their resemblance to each other, other than that it was just a slight genetic occurrence. Being no more than recurring characters at best, there's really no need to craft some elaborate splainin.
But if one had to, I suppose it's always possible that they're identical sisters, at least identical cousins. Being cousins would seem more likely, and not very close, as Ted's Mom on 'How I Met Your Mother' lives out in Ohio and doesn't get back to NYC very often.
But then you should drag in all the other characters she has played in the past as well, from 'Picket Fences', 'Providence', ,Charmed' and 'Grace Under Fire' to one-shots like 'Saved', 'Crossing Jordan', 'CSI' and 'NCIS'. And on and on......
Better to just stick with the internal differences splainin and be done with it!