Here are steps on how to do multiple exposure shots with your Lomo LC-A+
Note that only the Lomo LC-A+ have the Multiple Exposure (MX) features for older Lomo LC-A versions do not have this.
Press the shutter of your Lomo LC-A+. At the bottom of your Lomo LC-A+, you will find the MX slider. Slide the MX using your finger. This will release the shutter button of your Lomo LC-A+ and will allow you to click on the shutter again.
Press the shutter of your Lomo LC-A+ again. You can repeat this process to have multiple exposure shots.