On Mon, 27 Oct 2014, micky wrote:

How can the same FM station appear at two different spots on the dial?

--snip--

I lose track of which radios those are, so I'll start tuning at 88.1 and
tune up very gradually. After a period of silence, when I get above
88.5 to what I'd estimate is 88.6 or .7 or .8 I get 88.1 again.

How is that happening? I know about harmonics, but that doesn't apply,
does it?

My initial thought was that perhaps the station is operating a
"translator" (repeater) on 88.7-ish, but a search of the FCC database
doesn't turn up anything. There are two translators licensed to Maryland
on 88.7 MHz: W204BA in Oakland and W204CL in Lexington Park. Both belong
to Grace Missionary Church (d/b/a Grace Christian School). Some Googling
shows those affiliated with a small religious radio network, but it's
possible they could be re-transmitting 88.1 for some reason. Both
transmitters are fairly low power, as is typical of translators (250 and
55 watts, respectively), and given the distance (2-3 hours away) I doubt
there would be much overlap in coverage area, if any.

So... that possibility fairly well eliminated, I think the best bet is to
zip off an e-mail to the station and ask what's going on. Looks like
those are public radio stations, and my experience has been that the
engineers at those types of facilities are typically pretty helpful when
it comes to resolving reception concerns and addressing technical
questions. If you do that, I'd be curious what you dig up.

Since you are able to reproduce the behavior on multiple radios, I doubt
it's a problem with the receivers.