Not a good analogy.
In Crown heights just about everybody has two pairs of tefillin and gives both in together to get checked.
when people buy challah they buy based on how much will get eaten, not based on pairs of lechem mishna.
In short: in Crown Heights people check tefillin in pairs, people do not buy challah in pairs.
+1
I can see both sides of the argument. Either way, disclosure in advertising is the high road that any upstanding advertiser should take (IMHO).
There's an additional ambiguity with tefillin vs. mezuzah/challah where tefillin (like, lehavdil, pants) is already plural, so it's harder to distinguish between one pair or two.