2 IP addresses into 1 IP address

I use a load balance broadband router in order to double or triple the speed of my internet connection, as it allows multiple WAN entries, which are then used all together into one much faster speed, double or triple speed.

The problem is that some sites detect 2 or 3 different simultaneous external IP addresses requesting packets, which issues security flags. Not good.

I want to avoid this by only having 1 external ip address, but with the combined speed of multiple wan connections.

I know I can get 1 external ip address by connecting to an external proxy with the right protocol. I don't want to use that.

Is it possible to do this on my PC?

An idea would be connecting my desktop to a server-side proxy on my computer, which combines the ip addresses for example. And then connects to whichever external site I want.

The external site would only see one ip address, obviously.

Why should you have to collapse your WAN into one IP address?

Security or rate limits based on a single IP addresses will be a problem as you implement IPv6 and move away from NAT. Hosts having their own IP addresses is normal. Talk to the sites and services you use about better, application level authentication, and less precise IP address restrictions. If you have provided authentication factors, have logged in via the same device, and have an IP address on the same continent, there is not much reason to be suspicious.

Having multiple WAN links means you can diversify across different ISPs. Should the ISP changing between different flows trigger some sites' security, that's a problem. Consider getting provider independent IP space, where your flows are sourced from your own IP ranges. Ron Maupin implied this as an option in comments.