Way to combine 2+ Internet connections

[capital_one]

Does anyone know of a way to combine 2+ Internet connections from same or different ISPs to act as 1 single ISP

Example, say you have 2 modems with 2mbps down each and on combination the total bandwidth doubles to 4mbps throughput as they seamlessly act as one connection.

 

[grid12]

You could use a dual WAN router, but 1) you won't get a true 2+2 because of load balancing you will more than likely just get the 2 unless you are maxing out your connection. Also windows does not like this and will more than likely give you errors.