I have no knowledge to disagree. I do not know how accurate the book is. The book appears to use the 1905 description of the flag and says "The flag is of extra large size, and is mad of red material, the lettering being white and perfectly distinct."
Yes they are probably the same flag. In 1905 when they looked at the flag, the yellow lettering may have fadded to white making them believe the letters were white. Modern examination can determine the original color of the letters.