OTBI Date Prompts for two analyses in order to compare data fields

Summary:

OTBI Date Prompts for two analyses in order to compare data fields. I used the instructions of this page OTBI HCM historical reporting (v-cdn.net) to set the date as variable prompt in the analyses, due to the fact that I have to use Workforce Management - Position Real Time as the Subject Area. The analyses are exactly the same. The requirement is to compare the data of two dates. If I use a dashboard the date prompts are showing the same dates, even when I only select the date for one analyses. Dos anyone of you have an idea how to approach this? Maybe my approach has to be changed from scratch.