diff --git a/external/pdal_wrench/alg.cpp b/external/pdal_wrench/alg.cpp
index 7a92bc09f6e..7da639625e8 100644
--- a/external/pdal_wrench/alg.cpp
+++ b/external/pdal_wrench/alg.cpp
@@ -173,3 +173,15 @@ void removeFiles(const std::vector<std::string> &tileOutputFiles, bool removePar
         fs::remove(outputDir);
     }
 }
+
+fs::path fileStem(const std::string &filename)
+{
+    fs::path inputBasename = fs::path(filename).stem();
+            
+    while(inputBasename.has_extension())
+    {
+        inputBasename = inputBasename.stem(); 
+    }
+
+    return inputBasename;
+}
\ No newline at end of file
diff --git a/external/pdal_wrench/alg.hpp b/external/pdal_wrench/alg.hpp
index 441dc457908..2f311a468fc 100644
--- a/external/pdal_wrench/alg.hpp
+++ b/external/pdal_wrench/alg.hpp
@@ -93,6 +93,8 @@ bool runAlg(std::vector<std::string> args, Alg &alg);
 
 void removeFiles(const std::vector<std::string> &tileOutputFiles, bool removeParentDirIfEmpty = true);
 
+fs::path fileStem(const std::string &filename);
+
 //////////////
 
 
diff --git a/external/pdal_wrench/clip.cpp b/external/pdal_wrench/clip.cpp
index 04ec8fd2845..300f8841b75 100644
--- a/external/pdal_wrench/clip.cpp
+++ b/external/pdal_wrench/clip.cpp
@@ -191,7 +191,7 @@ void Clip::preparePipelines(std::vector<std::unique_ptr<PipelineManager>>& pipel
 
             // for input file /x/y/z.las that goes to /tmp/hello.vpc,
             // individual output file will be called /tmp/hello/z.las
-            fs::path inputBasename = fs::path(f.filename).stem();
+            fs::path inputBasename = fileStem(f.filename);
             
             // if the output is not VPC  las file format is forced to avoid time spent on compression, files will be later merged into single output and removed anyways
             if (!ends_with(outputFile, ".vpc"))
diff --git a/external/pdal_wrench/merge.cpp b/external/pdal_wrench/merge.cpp
index 2b767ea76b6..64e4e58be76 100644
--- a/external/pdal_wrench/merge.cpp
+++ b/external/pdal_wrench/merge.cpp
@@ -99,6 +99,18 @@ static std::unique_ptr<PipelineManager> pipeline(ParallelJobInfo *tile)
         last.push_back(filterExpr);
     }
 
+    // this is a special case for merging COPC files
+    // writers.copc does not support multiple inputs
+    //  merge step is necessary before writing the output
+    if (ends_with(tile->outputFilename, ".copc.laz"))
+    {
+        Stage *merge = &manager->makeFilter("filters.merge");
+        for (Stage *stage : last)
+            merge->setInput(*stage);
+        last.clear();
+        last.push_back(merge);
+    }
+
     pdal::Options options;
     options.add(pdal::Option("forward", "all"));
     Stage* writer = &manager->makeWriter(tile->outputFilename, "", options);
@@ -138,8 +150,10 @@ void Merge::preparePipelines(std::vector<std::unique_ptr<PipelineManager>>& pipe
 
             VirtualPointCloud vpc;
             if (!vpc.read(inputFile))
+            {
                 std::cerr << "could not open input VPC: " << inputFile << std::endl;
                 return;
+            }
             
             for (const VirtualPointCloud::File& vpcSingleFile : vpc.files)
             {
diff --git a/external/pdal_wrench/thin.cpp b/external/pdal_wrench/thin.cpp
index 23e8c2907af..2b5a3644fa2 100644
--- a/external/pdal_wrench/thin.cpp
+++ b/external/pdal_wrench/thin.cpp
@@ -167,7 +167,7 @@ void Thin::preparePipelines(std::vector<std::unique_ptr<PipelineManager>>& pipel
 
             // for input file /x/y/z.las that goes to /tmp/hello.vpc,
             // individual output file will be called /tmp/hello/z.las
-            fs::path inputBasename = fs::path(f.filename).stem();
+            fs::path inputBasename = fileStem(f.filename);
 
             if (!ends_with(outputFile, ".vpc"))
                 tile.outputFilename = (outputSubdir / inputBasename).string() + ".las";
diff --git a/external/pdal_wrench/to_vector.cpp b/external/pdal_wrench/to_vector.cpp
index 5ac8ae0a651..3bdd82b45e0 100644
--- a/external/pdal_wrench/to_vector.cpp
+++ b/external/pdal_wrench/to_vector.cpp
@@ -112,7 +112,7 @@ void ToVector::preparePipelines(std::vector<std::unique_ptr<PipelineManager>>& p
 
             // for input file /x/y/z.las that goes to /tmp/hello.vpc,
             // individual output file will be called /tmp/hello/z.las
-            fs::path inputBasename = fs::path(f.filename).stem();
+            fs::path inputBasename = fileStem(f.filename);
             tile.outputFilename = (outputSubdir / inputBasename).string() + ".gpkg";
 
             tileOutputFiles.push_back(tile.outputFilename);
diff --git a/external/pdal_wrench/translate.cpp b/external/pdal_wrench/translate.cpp
index 62ce15d0619..2d92948d172 100644
--- a/external/pdal_wrench/translate.cpp
+++ b/external/pdal_wrench/translate.cpp
@@ -169,12 +169,12 @@ void Translate::preparePipelines(std::vector<std::unique_ptr<PipelineManager>>&
 
             // for input file /x/y/z.las that goes to /tmp/hello.vpc,
             // individual output file will be called /tmp/hello/z.las
-            fs::path inputBasename = fs::path(f.filename).stem();
+            fs::path inputBasename = fileStem(f.filename);
 
             if (!ends_with(outputFile, ".vpc"))
                 tile.outputFilename = (outputSubdir / inputBasename).string() + ".las";
             else
-                tile.outputFilename = (outputSubdir / inputBasename).string() + outputFormat;
+                tile.outputFilename = (outputSubdir / inputBasename).string() + "." + outputFormat;
 
             tileOutputFiles.push_back(tile.outputFilename);