I'm observing occasional key bouncing as well on the T1 (with FBReader).
From comparing Sony's Linux kernel sources of the T2 and the T1, it looks like the T1 and T2 have some chatter / bouncing on the I/O interface connecting the buttons. The T2 kernel's gpio_keys driver contains a kernel-level workaround that attempts to hide the bouncing.
Unfortunately, I don't know whether anyone has managed to get a self-compiled kernel to run on the T1 yet (
e-ink's experiments looked promising, though). Once that's done, it should be possible to fix the T1 kernel as well.