it shows pin Arduino pins 52 & 51 (Atmega pins 20 & 21) as SDA and SCL.
Digital pins 21 & 20 (Atmega pins 43 & 44) are also labeled SCL and SDA.
No the I2C lines are on pins 20 & 21, where as the clock and data for the SPI interface are on pins 51 & 52, it might not be clear but it is not wrong.