Shares of Dollar General Corp. (DG)  flew higher Thursday, closing higher by 4.75% to $93.44. 

The rally comes despite the company's in-line earnings per share results and miss on revenue expectations. However, the quarter was better than it appears.

"We're starting to understand that there are no longer two big, serious dollar store competitors," TheStreet's Jim Cramer said on CNBC's "Mad Dash" segment.

Instead, Dollar General is the clear No. 1 while Dollar Tree, Inc. (DLTR) is a distant second. Shares of the latter are still recovering from heavy losses a week ago, which should come as little surprise to investors as Cramer called the selloff an overreaction.

In any regard, Dollar General is clearly in the driver's seat. Comp-store sales of 3.3% topped analysts' expectations for 2.6% growth. Gross margins rose and guidance came in well ahead of expectations.

Management expects full-year fiscal 2019 earnings of $5.95 to $6.15 per share. Analysts were only looking for earnings of $5.58 per share, noted Cramer, who also manages the Action Alerts PLUS charitable trust portfolio.

Family Dollar, a $9.2 billion acquisition by Dollar Tree, has not worked out well for the latter. Management has had trouble integrating the two businesses and the deal may have been a "bridge too far," he reasoned.

Meanwhile, Dollar General continues to expand and grow its market share.

This is no longer a duopoly, Cramer reasoned, adding that "there's only one dollar store you want to invest in and that's Dollar General -- even as I told you I like shopping at Dollar Tree much more."

At the time of publication, Cramer's Action Alerts PLUS had no position in any security mentioned.