Penalties for duplicate content

[jpuzakov]

Hello!We have a website with various city tours and activities listed on a single page (http://vaiduokliai.lt/). The list changes accordingly depending on filtering (birthday in Vilnius, bachelor party in Kaunas, etc.). The URL doesn't change. Content changes dynamically. We need to make URL visible for each category, then optimize it for different keywords (for example city tours in Vilnius for a list of tours and activities in Vilnius with appropriate URL /tours-in-Vilnius).The problem is that activities overlap very often in different categories, so there will be a lot of duplicate content on different pages. In such case, how severe penalty could be for duplicate content?

[JordanLowry]

According to Matt Cutts and various other blogs etc there is no duplicate content penalty. However if it is spammy then you could incur a potential penalty.