Typically, investors invest in companies, not in products. Most companies don't end up with the same idea they had when they got started, and smart investors know this. So even though you have attracted an investor with a specific app, that investor will expect a return on your other apps as well.
One problem that I see with your situation is if your investors think you are only developing the one app that they like. That an investor may feel like you are spreading yourself too thin trying to develop three apps at once. This is probably something best addressed soon, before it gets out of hand.
The bottom line is that your pitch should be for your company, not for a specific app.
Are the two investors interested in the same two apps? Or each one with different ones.
The Lovin' Spoonfuls song Did You Ever Have to Make Up Your Mind? comes to mind.
I would think that each investor believes that you will be 100% committed to their project, so I don't believe you will have a good reaction from them if they learn about your other efforts though another channel.
Do you really have the resources / bandwidth to launch three apps? They may all be good ideas, but bringing one app from concept to production is a challenge.
Pick the best one, get it going, and then leave the other two for another time (or for self funding at a later stage).
Or - If the products naturally go together, then sell your companies ability to launch, iterate & learn rather than the individual products.