I used to use one stick - and found that I was leaning to the stick side, with adverse effects on the shoulder on that side.
My physio suggested two sticks so that I was walking upright - this was an improvement.
The best thing is to try to get to the bottom of what is causing you to stumble. Could it be the start of a dropped foot (or feet)?
You can sample walking with a wheeled aid with your everyday supermarket shopping trolley. Park the stick in the trolley and go slowly round the store.
Stumbling and/or tripping are not always the same thing as a "pure" balance problem. In my own case, just covering my eyes for a moment is enough to have me starting to lean sideways. A lack of condition in one or more of the leg muscles is enough to start a slow collapse to one side (or backward). But, if it really is tripping/stumbling - try to note if this is a case of one or both feet catching on the floor/carpet/rugs/pavement, etc. Then you have to try and work out if it is the foor that is not coming up, or if a knee (or knees) is not bending enough.
If it is the start of "dropped foot", then a fixed orthotics device may be sufficient. But to get any help, you need to get to see a Physio who can advise you properly from personal observation. and refer you to Orthotics as appropriate. It might be that what you need is FES, but that could depend on the current NHS policy in your area.