There's been an idea of another Earth on the opposite side of the sun to us for decades. Sadly, it was disproved by satellites and probes that have used the sun for a slingshot into the outer Solar System.
It was once thought that Mars was inhabited, especially when those 'canals' were viewed and Edgar Rice Burroughs wrote all about it. Sadly, this was all disproved by actually going there.
It was also thought that Venus shared a similar fate and ERB wrote all about that, too. Sadly...etc..
The latest science reports on Venus make interesting, but ultimately disappointing reading.
Around this particular star, it does appear that we are alone.
That said, the oceans remain largely unexplored and who's to say Pellucidar doesn't exist?*
It is likely that there is life, even what we might recognise as 'intelligent' life out there, but the problem isn't one of distance, but of time.
Our life form and subsequent civilisation has only existed within the merest blink of Time, which is truly vast. It will likely still be only a blink, when we are long extinct.
The chances of our 'blink' coinciding with that 'blink' of another intelligent life form are somewhat remote. However, given that stuff doesn't decay at a rapid rate in space, it is remotely possible that we might find remnants of extinct civilisations...and that brings forth all manner of interesting possibilities.
*Okay, I admit it...I like ERB.