It's hard to say for certain exactly how Karloff and Lugosi really felt about their filmic "friendly rivalry". I'd like to believe that, considering the nature of their personalities, they felt a warmness to each other, despite the fact that Karloff had the upper hand in popularity -- and more importantly -- finances. Karloff was grateful, Lugosi was proud, and together they made beautiful movies together.
One of those was Universal's 1934 classic story of Satanism and murder, THE BLACK CAT. The July 1934 issue of MODERN SCREEN showed a picture of Karloff and Lugosi on the set of their first film together, hyped with the promise to out-Frankenstein FRANKENSTIEN and out-Dracula DRACULA!