You can always have multiple network connections on any PC. However, for any given network, whether local (e.g., 192.168.1.x) or the internet, your PC will always choose one and ignore all others. Windows will NOT aggregate/bond them to increase your bandwidth.
That said, it may be possible to buy a multi-WAN router that supports both technologies. Although the multi-WAN router wouldn’t actually bond the broadband connections, clients would see the router as one, logical, internet gateway. The multi-WAN router would, in round robin fashion, use both broadband connections to service all your clients, and provide failover protection (if one drops, the other takes over).
But you may not be able to find a multi-WAN router that supports both technologies, and one that you can afford. There's always the possibility to "roll your own" using a PC, router software, etc. Definitely not for the beginner or non-techie, but is probably doable by an experienced user.