Here's another piece of engineering history I stumbled on during my longer than normal return from Europe, i.e., Paris - Dublin - Boston. A long time ago, I was general manager of the MIT college radio station (now WMBR, then WTBS but that's another story). The history of broadcast radio as I understood it then (and up until last week) was that Westinghouse started broadcasting in Pittsburgh in 1920 under the call sign KDKA.
But a history article in the June issue of the Proceedings of the IEEE points out that Westinghouse only started after they noticed the success their employee, Frank Conrad, was having broadcasting music using recordings loaned to him by a local merchant on the condition that the store be mentioned during the broadcasts.
So now that I'm back online, I've looked at the history of KDKA and find, not only did Frank Conrad's private efforts predate KDKA, but a Canadian station (initially XWA, then CFCF and CIQC) actually started in 1919 and went to a regular schedule six months before KDKA. There's a more complete history of Frank Conrad & KDKA on the KDKA site here. The Canadians are quiet, as their successor station "940 Montreal" doesn't even list their call letters on their website, let alone their history.
In short, as with most human endeavors, there were multiple similar efforts happening, in parallel.