There is an iwloc parameter that determines where to indicate the info window.
I don't know where it is documented somewhere, but it looks like it works as follows:
If the iwloc parameter is absent, the info industry is displayed for the first marker (place), and the A-marker is available
When the iwloc parameter is present and is set to a value from AJ, an index pointer is displayed for the marker (location) with the index specified through the iwloc parameter when the marker (location) exists.
So what to do: add the iwloc parameter to iframe-src with a value other than AJ, for example:
&iwloc=false
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