A non-inverting buffer cannot be done directly, as the smallest building block you can make is an inverter, and two inverters make a buffer.
Two inverters in a row means it adds more delay, but it also has a higher output drive capability. Internally, it could have any even amount of inverters connected together to make a buffer with required drive ability, as each stage can roughly amplify the drive ability by about 4x.
Sometimes you see the inverting notation on logic gate inputs and outputs, it might simply mean that this is a buffer for an active-low signal, and both the input and output inverting notation is there to emphasize that.