ででもある instead of でもある?
Hello!
I just encountered the following sentence in a text I was reading.
その思い出が不愉快ででもあるかように、彼は口早にそう言った。
I get that the meaning is something along the lines of "He said it quickly, as if this memory made him feel uneasy", but I'm confused by the 不愉快ででもある
I know that でもある is sometimes used when も alone cannot be used grammatically (例えば、「彼は日本人です。アメリカ人でもあります。」), but the additional で is really confusing to me. Can anyone explain why it is there?
Thank you so much!