How are you measuring this?
In a nutshell speed is not aggregated, as you cannot load balance the packets, only the connections. So you'd need some benchmark which opens multiple connections, like a torrent.
You could aggregate the packets if you had a server in the internet with at least 4Gbps connection and you would create 2 tunnels from OpenWrt to that server, then bond the tunnels.
It should be so when we think logically.
2 x 930 download mbps speed.
total speed should be in the range of 1860 - 1800 mbps.
because I can get it in upload, it's 114 mbps.
The upload speed doubles, so the upload speed I get in a single pppoe is 57mbps, when I combine it with mwan, I can reach 114 mbps. but why doesn't the same apply to download?