Dollar General (DG) investors were happy to see a double-digit rally in shares after earnings. Arun Sundaram doesn't see those gains lasting. He points out the company's underperformance over recent years and a lack of in-store traffic growth as bearish signs for Dollar General. Ahead of Dollar Tree's (DLTR) earnings Wednesday, Arun notes the company's tariff exposure as a risk but cites price increases as a positive. George Tsilis later turns to options trades for both discount stores.