I am wondering more specifically in regards to the experience of Elector Palatine Frederick V. Given that both the Palatinate and Bohemia were electoral territories, upon becoming King of Bohemia in 1619, did Frederick technically hold two votes in the Imperial electoral college? Are there any other examples of an individual in the Holy Roman Empire holding dual elector titles?
The electoral college was not about to give that much power to one individual. Instead of acknowledging the election of Frederick V of the Palatine as King of Bohemia, the electoral college as a whole confirmed Ferdinand II as king, ignoring his previous deposition from that kingdom (which led to Frederick's election), and, for good measure, refused to receive a delegation from Bohemia, with only the Palatine delegation objecting.
If you're interested:
Purcell, Brennan C. (2003), The Winter King: Frederick V of the Palatinate and the Coming of the Thirty Years' War, London: Ashgate.