The glyph at code point U+211D should look like a double-struck capital R, but instead looks like the black-letter capital R that should be at U+211C. The glyph at U+211C looks like a double-struct capital Q, which should be at U+211A. These glyphs are both correct in sans but broken in serif.
Thanks for your report.
DejaVu Serif currently doesn't include 211C or 211D, so its likely a problem with another font on your system thats 'peeking through the gaps'.
Mass move of freetype bugs to the new freetype product
Reopen the NOTOURBUG reports now they're correctly affected