I know of two markets that actually had three side-by-side full-power analog VHF channels.
In the Greenville-New Bern-Washington, NC market, you had channels 7, 8 and 9. There was just channels 7 (WITN, Washington) and 9 (WNCT, Greenville) until 1989, when WFXI in Morehead City signed on VHF channel 8. Of course, the antenna was directional and positoned well southeast of 7 and 9's combined stick near Grifton, NC to protect them and co-channel WRIC in Petersburg, Virginia.
Something similar happened next-door in the Norfolk-Portsmouth-Newport News, VA-NC, market with channels 2, 3 and 4. Since 1965, you already had a channel 2 (WUND, Columbia) and a channel 3 (WTKR, Norfolk) operating side-by-side, and non-directional, though separated by 70 miles or so. WUND was technically in the Greenville-Washington-New Bern market until relicensing to Edenton in the mid-2000s. In 2001, WSKY in Manteo signed on VHF channel 4, with a directional antenna, but much closer to WTKR's transmitter in Driver, Virginia. Channels 2, 3 and 4 served a large common area and, towards the end of analog TV, all did so as a part of the same TV market.
There may be other examples out there as well. Another interesting note on VHF is that channels 4 and 5, as well as channels 6 and 7 can operate in the same market beside each other since there's sufficient space between the frequeicies at which they operate. It's very common to see channels 4 and 5 assigned to the same market (Raleigh-Durham, Washington, Charleston, New York City, Dallas-Fort Worth, Los Angeles, Seattle, Nashville, Boston, Oklahoma City, Salt Lake City, et al) and, to a lesser extent, channels 6 and 7 (Miami-Fort Lauderdale and Omaha are the only ones that come to mind). I'm not sure why the popularity for the 4-5 combos versus the 6-7 combos, though alot of that depended on surrounding markets and what was alloted there.