If the "Price-Earning Ratio" of two companies are same and they merge on the basis of share swap ratio…

Since $\text{Market Price per Share (MPS)} = \text{P/E Ratio} \times \text{EPS}$, when two merging companies have the same P/E ratio ($\text{P/E}_1 = \text{P/E}_2$), the ratio of their market prices equals the ratio of their earnings per share ($\text{MPS}_1 / \text{MPS}_2 = \text{EPS}_1 / \text{EPS}_2$). An EPS-based share swap ratio therefore equals the market-price swap ratio, protecting both market value and earnings for both groups of shareholders.