multiple VLANs on the same subnet

Hi there,
First, we don't suggest use vlan1 when there are more than one vlan on S5700, because all interfaces on S5700 are allowed passed vlan 1. If you insist on using vlan1, please use undo allow pass vlan 1 on all access tpye interface on all switches.
Second, use different vlan will not increase the bandwith.  In my opinon, you can add GE0/0/1 and GE0/0/2 to eth-trunk 1 to increase the bandwith. You can find how to config it in below link:

http://support.huawei.com/hedex/hdx.do?lib=EDOC1000135317AEG0221R&docid=EDOC1000135317&lang=en&v=04&tocLib=EDOC1000135317AEG0221R&tocV=04&id=dc_cfg_eth-trunk_cd&tocURL=resources%2fdc%2fdc%5fcfg%5feth%2dtrunk%5fcd%2ehtml&p=t&fe=1&ui=3&keyword=aggreg&keyword=configur