Complex sentence: There have previously been "Dukes of Scania" in the House of Bernadotte, two Crown Princes who became Kings Charles XV in 1859 and Gustaf VI Adolf in 1950.
Split into simpler sentences: There have previously been two "Dukes of Scania" in the House of Bernadotte. The previous Dukes were Crown Princes who were crowned Charles XV in 1859, and Gustaf VI Adolf in 1950.