Is it normal to have alpha and beta packages installed on LTS release by default?

On a server I manage I noticed that there are installed packages that are marked as alpha or beta. As far as I know, I have only installed packages from default repositories and have not enabled any testing repository or installed packages from unofficial sources.

If it is normal to have alpha or beta versions on LTS release, are they stable enough to be reliable for production use?

My server version:

```
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.2 LTS
Release:        16.04
Codename:       xenial

```

Alpha and beta packages installed on the server:

```
dpkg -l |egrep "beta|alpha"
ii  grub-common                      2.02~beta2-36ubuntu3.8             amd64        GRand Unified Bootloader (common files)
ii  grub-pc                          2.02~beta2-36ubuntu3.8             amd64        GRand Unified Bootloader, version 2 (PC/BIOS version)
ii  grub-pc-bin                      2.02~beta2-36ubuntu3.8             amd64        GRand Unified Bootloader, version 2 (PC/BIOS binaries)
ii  grub2-common                     2.02~beta2-36ubuntu3.8             amd64        GRand Unified Bootloader (common files for version 2)
ii  liblzma5:amd64                   5.1.1alpha+20120614-2ubuntu2       amd64        XZ-format compression library
ii  python-apt-common                1.1.0~beta1build1                  all          Python interface to libapt-pkg (locales)
ii  python3-apt                      1.1.0~beta1build1                  amd64        Python 3 interface to libapt-pkg
ii  xz-utils                         5.1.1alpha+20120614-2ubuntu2       amd64        XZ-format compression utilities

```

This is what I have at `/etc/apt/sources.list`:

```
deb http://archive.ubuntu.com/ubuntu/ xenial main restricted
deb-src http://archive.ubuntu.com/ubuntu xenial main restricted

deb http://archive.ubuntu.com/ubuntu/ xenial-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu xenial-updates main restricted

deb http://archive.ubuntu.com/ubuntu/ xenial universe
deb-src http://archive.ubuntu.com/ubuntu xenial universe
deb http://archive.ubuntu.com/ubuntu/ xenial-updates universe
deb-src http://archive.ubuntu.com/ubuntu xenial-updates universe

deb http://archive.ubuntu.com/ubuntu/ xenial multiverse
deb-src http://archive.ubuntu.com/ubuntu xenial multiverse
deb http://archive.ubuntu.com/ubuntu/ xenial-updates multiverse
deb-src http://archive.ubuntu.com/ubuntu xenial-updates multiverse

deb http://archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu xenial-backports main restricted universe multiverse

deb http://archive.ubuntu.com/ubuntu/ xenial-security main restricted
deb-src http://archive.ubuntu.com/ubuntu xenial-security main restricted
deb http://archive.ubuntu.com/ubuntu/ xenial-security universe
deb-src http://archive.ubuntu.com/ubuntu xenial-security universe
deb http://archive.ubuntu.com/ubuntu/ xenial-security multiverse
deb-src http://archive.ubuntu.com/ubuntu xenial-security multiverse

```