However, you can link two accounts together to increase your max number of campaigns. With linked accounts, only one ad will show at a time regardless of what account contains what keywords (or even duplicates).
The major issue is that reports aren't consolidated, so either you can put the accounts under an MCC and run reports for both accounts at once to combine the data, or you have to run two separate reports and combine the data.
Hard Limits:
2000 keywords keyword per Ad Group
25 active campaigns (paused and deleted campaigns don't count against this limit)
Some accounts have 1MM keyword limits - where I do believe it's a hard stop at that point. We've also worked with accounts that far surpass 25 active campaigns within one account.