In reply to Meeta:
You say the two seq_item objects are randomized at the same time, but that is not the same as simultaneously. randomize() and sample() are procedural statements executing discretely. To achieve the cross you want, you need to get all the data you want in the cross into a single sample(). That may mean creating a separate coverage collection component, using analysis ports to do a write() from the two agents to your collector. Then you will need to merge the data so a single covergroup can sample it.