Hoppy's Seeing Double
There is trouble as Bar 20 as someone is rustling cattle and Hoppy (William Boyd) has his suspicions who is behind it. Those suspicions fall on Earl Brennan and Dave Talbot, twins with one owning a casino whilst the other is a rancher. Believing that one creates an alibi for the other whilst he is off rustling, Hoppy decides to head undercover as a gambler to prove his theory right. Unfortunately having got a job at the casino a gunslinger recognizes Hoppy and puts him in danger.
I'm not entirely sure how many Hopalong Cassidy movies I have watched but it is a fair few and that I am sure is influential when I say what whilst "Silver on the Sage" is a good Hopalong western it does follow use a western staple which was used in a variety of movies back in the 1930's and 40s. That staple is are hero going undercover to find out who a bad guy is but ending up in trouble when his cover is threatened.
But whilst "Silver on the Sage" delivers much of what was not just typical about Hopalong movies but what you typically expected it does have the entertaining set up involving duplicitous twins. Not that twins in a western is that original either as a few westerns also used the idea but it was not a commonly used one and so has some entertainment value.
What this all boils down to is that whilst "Silver on the Sage" has some good ideas it is pretty regular Hopalong Cassidy western which these days whilst enjoyable is nothing special.